>>> TONIGHT, KAMALA HARRIS HOLDING THE FIRST RALLY OF HER >>> TONIGHT, KAMALA HARRIS HOLDING THE FIRST RALLY OF HER NEW PRESIDENTIAL CAMPAIGN AS PRESIDENT BIDEN PREPARES TO ADDRESS THE NATION. HARRIS TAKING THE STAGE IN BATTLEGROUND WISCONSIN AS THE DEMOCRATS' DE FACTO NOMINEE. HER SUPPORT IN THE PARTY GROWING, TODAY WINNING ENDORSEMENTS FROM THE TOP TWO DEMOCRATS IN CONGRESS. AND OUR NEW REPORTING ON HER VEEPSTAKES. WHO IS ON HER SHORT LIST, AND WILL WE SEE A KAMALA HARRIS-DONALD TRUMP DEBATE? ALL THIS AS PRESIDENT BIDEN ENDS HIS COVID ISOLATION AND TRAVELS BACK TO THE WHITE HOUSE. THE MAJOR PRIME-TIME ADDRESS HE PLANS TO GIVE ABOUT HIS DECISION TO DROP OUT. >>> ALSO TONIGHT, THE SECRET SERVICE DIRECTOR RESIGNING A DAY AFTER TAKING HEAT FROM CONGRESS OVER THE FAILURE TO PREVENT THE ASSASSINATION ATTEMPT ON DONALD TRUMP. >>> ON CAPITOL HILL, PROTESTERS ARRESTED AHEAD OF ISRAELI PRIME MINISTER BENJAMIN NETANYAHU'S ADDRESS TO CONGRESS. AND WHAT NETANYAHU SAID AFTER ARRIVING IN THE U.S. THAT'S RAISING NEW HOPE OF A CEASEFIRE. >>> DELTA AIRLINES CANCELING HUNDREDS MORE FLIGHTS FOR A FIFTH DAY. NOW THE FEDS LAUNCHING AN INVESTIGATION. >>> CAUGHT ON CAMERA, THE WHALE LANDING ON A BOAT OFF NEW HAMPSHIRE. >>> PLUS, THE MASSIVE EXPLOSION AT YELLOWSTONE. >>> AND BACK IN TIME TO 1924. HOW THE OLYMPICS HAVE CHANGED IN THE CENTURY SINCE PARIS LAST HOSTED THE GAMES. >> Announcer: THIS IS "NBC NIGHTLY NEWS" WITH LESTER HOLT. >> GOOD EVENING AND WELCOME. SHE HAS JOINED THE FRAY LATE, BUT VICE PRESIDENT KAMALA HARRIS IS QUICKLY ADVANCING HER ATTACK STRATEGY AGAINST FORMER PRESIDENT TRUMP AS SHE CONSOLIDATES HER SUPPORT AMONG DEMOCRATIC DELEGATES AND NOW THE PARTY'S TOP LEADERS IN CONGRESS. AT HER FIRST RALLY SINCE PRESIDENT BIDEN EXITED THE RACE TWO DAYS AGO, VICE PRESIDENT HARRIS LAUNCHING INTO MR. TRUMP TODAY, COMPARING HIM TO THE WRONGDOERS SHE ONCE WENT AFTER AS A PROSECUTOR. "I KNOW DONALD TRUMP'S TYPE," SHE TOLD A FIRED UP CROWD IN BATTLEGROUND, WISCONSIN. TONIGHT EXPRESSIONS OF SUPPORT AMONG DELEGATES POSITION HER AS THE FRONT-RUNNER FOR THE DEMOCRATIC NOMINATION. AND TODAY SECURING THE ENDORSEMENTS OF THE TOP DEMOCRATS IN CONGRESS. BUT THE MAN DEMOCRATS HOPE TO DEFEAT IS FIRING BACK. DONALD TRUMP PAINTING MS. HARRIS AND MR. BIDEN AS ONE AS THE SAME. PETER ALEXANDER HAS LATE DEVELOPMENTS. >> Reporter: TONIGHT, VICE PRESIDENT KAMALA HARRIS HOLDING THE FIRST RALLY OF HER PRESIDENTIAL CAMPAIGN IN FRONT OF AN ENERGIZED CROWD IN CRITICAL WISCONSIN, EMBRACING HER LIKELY SHOWDOWN WITH FORMER PRESIDENT TRUMP. >> I WILL PROUDLY PUT MY RECORD AGAINST HIS ANY DAY OF THE WEEK. >> Reporter: PITCHING HERSELF AS A FORMER PROSECUTOR, GOING AFTER HER POLITICAL RIVAL, A CONVICTED CRIMINAL. >> I TOOK ON PERPETRATORS OF ALL KINDS -- PREDATORS WHO ABUSED WOMEN. SO HEAR ME WHEN I SAY, I KNOW DONALD TRUMP'S TYPE. >> Reporter: ZEROING IN ON MR. TRUMP'S PRAISE OF THE SUPREME COURT FOR OVERTURNING ROE V. WADE. >> WE TRUST WOMEN TO MAKE DECISIONS ABOUT THEIR OWN BODIES AND NOT HAVE THEIR GOVERNMENT TELL THEM WHAT TO DO. >> Reporter: THE RAUCOUS EVENT COMING JUST HOURS AFTER HARRIS BECAME THE DE FACTO DEMOCRATIC NOMINEE. HER CAMPAIGN ANNOUNCING SHE SECURED PUBLIC SUPPORT FROM A MAJORITY OF THE PARTY'S DELEGATES AHEAD OF NEXT MONTH'S CONVENTION, TONIGHT WINNING ANOTHER PAIR OF KEY ENDORSEMENTS FROM THE TWO MOST POWERFUL DEMOCRATS IN CONGRESS. >> WE ARE HERE TODAY TO THROW OUR SUPPORT BEHIND VICE PRESIDENT KAMALA HARRIS. >> Reporter: AND TODAY HOLLYWOOD STAR GEORGE CLOONEY, JUST TWO WEEKS AFTER URGING PRESIDENT BIDEN TO DROP OUT, PRAISING HIM FOR SAVING DEMOCRACY ONCE AGAIN AND HAILING HARRIS' HISTORIC QUEST. LATE TODAY PRESIDENT BIDEN, WHO HAS NOW TESTED NEGATIVE FOR COVID WILL RETURN TO THE WHITE HOUSE WHERE HE'LL ADDRESS THE NATION FROM THE OVAL OFFICE TOMORROW NIGHT, DETAILING HIS DECISION TO LEAVE THE RACE FOLLOWING IMMENSE PRESSURE FROM DEMOCRATS, AND TO LAY OUT WHAT HE HOPES TO DO IN HIS FINAL SIX MONTHS IN OFFICE. THAT MUCH MORE DIFFICULT NOW AS A LAME DUCK. MR. TRUMP TODAY OFF THE TRAIL BUT ON HIS NEW MESSAGE, NOW ATTACKING HARRIS. >> SHE'S THE SAME AS BIDEN, BUT MUCH MORE RADICAL. SHE IS A RADICAL LEFT PERSON. AND THIS COUNTRY DOESN'T WANT A RADICAL LEFT PERSON TO DESTROY IT. >> Reporter: HIS RUNNING MATE J.D. VANCE OVERNIGHT ACCUSING DEMOCRAT ELITES OF DISREGARDING THE PROCESS THAT PRESIDENT BIDEN WON. >> DEMOCRATS ARE THE ONES WHO WANT TO THROW OUT 14 MILLION BALLOTS AND NOT ELECT KAMALA HARRIS BUT SELECT KAMALA HARRIS. IT'S DISGRACEFUL, AND THAT'S A THREAT TO AMERICAN DEMOCRACY. >> SO PETER WE ALL SAW THE IMPACT OF THE FIRST DEBATE AND FORMER PRESIDENT TRUMP WAS ASKED TODAY IF HE WOULD NOW DEBATE THE VICE PRESIDENT. WHAT DO WE KNOW? >> Reporter: LESTER, MR. TRUMP SAID HE WOULD ABSOLUTELY DEBATE VICE PRESIDENT HARRIS, ADDING HE WOULD BE WILLING TO DO MORE THAN ONE DEBATE, BUT TONIGHT HARRIS CAMPAIGN SAYING IN THE SAME COMMENTS MR. TRUMP ALSO APPEARS TO BE HEDGING WHETHER HE WILL SHOW UP FOR THE PREVIOUSLY PLANNED SEPTEMBER DEBATE. LESTER? >> PETER ALEXANDER, THANK YOU. >>> THERE IS GROWING ANTICIPATION ABOUT A HARRIS RUNNING MATE WITH JUST A SHORT WINDOW FOR HER TO DECIDE. HALLIE JACKSON JOINING US NOW. HALLIE, YOU'RE FOLLOWING THOSE IN THE RUNNING? >> THAT'S RIGHT, LESTER. THIS UNEXPECTED ROUND OF VEEPSTAKES IS PUTTING BATTLEGROUND AND BATTLEGROUND-ADJACENT GOVERNORS INTO THE SPOTLIGHT. THERE IS ROY COOPER OF NORTH CAROLINA WHO HAS KNOWN HARRIS FOR YEARS AS A FELLOW FORMER STATE ATTORNEY GENERAL. JOSH SHAPIRO OF PENNSYLVANIA, WHO WON OFFICE IN A LANDSLIDE THERE, TIM WALZ OF MINNESOTA, HEAD OF THE DEMOCRATIC GOVERNORS ASSOCIATION, AND GRETCHEN WHITMER OF MICHIGAN, WHO SAID SHE IS ONLY INTERESTED IN HER CURRENT JOB FOR NOW. THERE IS ALSO MARK KELLY, ARIZONA'S DEMOCRATIC SENATOR, WELL LIKED IN THAT CHAMBER. MULTIPLE SOURCES TELL NBC NEWS VETTING MATERIALS HAVE BEEN REQUESTED FROM ALL OF THEM. THERE IS ALSO SPECULATION ABOUT ANDY BESHEAR AND TRANSPORTATION SECRETARY PETE BUTTIGIEG. A SOURCE FAMILIAR WITH THE VP SELECTION PROCESS TELLS ME IT IS MOVING ALONG. THERE IS NO FIRM DEADLINE, BUT THE CAMPAIGN MAY WANT TO MAKE A PICK BEFORE AUGUST 7th TO AVOID POTENTIAL LEGAL CHALLENGES IF THE TICKET IS NOT SET THEN. LESTER? >> HALLIE, THANK YOU. >>> ALSO TONIGHT, THE HEAD OF THE SECRET SERVICE RESIGNING AFTER BIPARTISAN CALLS. IT COMES AFTER THE ATTEMPTED ASSASSINATION OF FORMER PRESIDENT TRUMP. JULIA AINSLEY NOW WITH LATE DETAILS ON THAT. >> MY NAME IS KIMBERLY CHEATLE -- >> Reporter: TONIGHT KIMBERLY CHEATLE, THE 29-YEAR VETERAN OF THE SECRET SERVICE IS OUT, IN A LETTER TO PRESIDENT BIDEN SAYING THE SECRET SERVICE'S SOLEMN MISSION IS TO PROTECT OUR NATION'S LEADERS. ON JULY 13th, WE FELL SHORT ON THAT MISSION. I TAKE FULL RESPONSIBILITY FOR THE SECURITY LAPSE. HER RESIGNATION FIRST REPORTED BY NBC NEWS, COMES NINE DAYS AFTER A GUNMAN TRIED TO ASSASSINATE DONALD TRUMP AT A RALLY, PUTTING CHEATLE IN THE HOT SEAT YESTERDAY AS SHE STRUGGLED TO ANSWER BASIC QUESTIONS. >> WHY WAS THE ROOFTOP LEFT NAKED TO BEGIN WITH, CAN YOU TELL US THAT? CONSIDERING IT WAS WITHIN THE LINE OF SIGHT AND SO VERY CLOSE. >> AGAIN, I CAN'T SPEAK TO THE SPECIFICS OF THIS PARTICULAR EVENT SITE. >> Reporter: THE DEPUTY DIRECTOR HAS NOW STEPPED IN TEMPORARILY. BUT QUESTIONS AND HARSH CRITICISM OF THE AGENCY PERSIST. COMMITTEE CHAIRMAN MARK GREEN HAS SUBPOENAED THE SECRET SERVICE. >> THE FACT THAT THERE WAS NOBODY COVERING THE TOP OF THAT BUILDING IS RIDICULOUS. >> Reporter: HE IS CALLING FOR EVEN MORE CHANGES, ESPECIALLY DURING THIS TENSE AND HIGH PROFILE ELECTION SEASON. >> WE'RE GOING TO CONTINUE TO LAY OUT ALL THE THINGS THAT WE THINK NEED TO BE ADDRESSED AND HOPE AND WATCH AND MAKE SURE THAT SECRET SERVICE IMPLEMENTS THOUGH. >> Reporter: FOR YEARS, THE AGENCY HAS HAD A STAFFING SHORTAGE, ONE OF THE REASONS SECRET SERVICE SOURCES TELL NBC NEWS IT DENIED SOME REQUESTS FOR MORE SECURITY AT EARLIER TRUMP EVENTS. THE SECRET SERVICE CURRENTLY HAS ABOUT 3500 AGENTS ASSIGNED TO PROTECTIVE DETAILS, INCLUDING NEW MORE ENHANCED SECURITY FOR VICE PRESIDENT KAMALA HARRIS. THAT'S 500 FEWER AGENTS THAN THEY HAD TEN YEARS AGO. PAUL ECKLOFF SERVED IN THE SECRET SERVICE FOR 23 YEARS. >> DIRECTOR CHEATLE NEEDED TO GO. SHE HAD LOST THE FAITH OF THE MEN AND WOMEN OF THE SECRET SERVICE. >> Reporter: WE'RE IN THE MIDDLE OF A CAMPAIGN SEASON. HOW MUCH TIME DOES THE SECRET SERVICE HAVE TO LEARN THE LESSONS AND FIX WHAT WENT WRONG? >> THE SIMPLE ANSWER IS THEY HAVE NO TIME. THEY HAVE TO INTEGRATE THE CHANGES NOW BEFORE ANOTHER TRAGEDY OCCURS. >> JULIA, WHAT KINDS OF CHANGES COULD THE SECRET SERVICE BE CONSIDERING HERE? >> Reporter: LESTER, EXPERTS SAY THEY COULD ASSESS HOW MUCH THEY DEPEND ON LOCAL LAW ENFORCEMENT, REVAMP THEIR RECRUITING PROCESS, AND INCREASE AERIAL SURVEILLANCE. BUT NOTHING HAS BEEN SET IN STONE YET. LESTER? >> JULIA AINSLEY, THANK YOU. >>> TONIGHT ISRAEL'S PRIME MINISTER, BENJAMIN NETANYAHU, IS IN WASHINGTON WITH A CEASEFIRE AND HOSTAGE DEAL HANGING IN THE BALANCE. ANDREA MITCHELL HAS MORE ON HIS HIGH-STAKES VISIT. >> Reporter: AT THE CAPITOL TODAY, HUNDREDS OF ANTI-WAR PROTESTERS AHEAD OF PRIME MINISTER NETANYAHU'S SPEECH HERE TOMORROW. THE CAPITOL POLICE MAKING ARRESTS, MEETING WITH AMERICAN HOSTAGE FAMILIES MONDAY NIGHT. NETANYAHU TELLING THEM THE CONDITIONS ARE RIPENING TO BRING THEIR LOVE ONES HOME IN THIS VIDEO RELEASED BY HIS OFFICE. FOR THE FIRST TIME THE PRIME MINISTER IS SIGNALING PROGRESS. BUT THE PARENTS OF AMERICAN HOSTAGE HIRSH GOLDBERG-POLIN TOLD NETANYAHU THEY WANT HIM TO ANNOUNCE A DEAL NOW. >> HE INDICATED LAST NIGHT THAT MAYBE IT'S NOT QUITE THERE. AND WE'RE NOT GOING TO STOP PUSHING. WE NEED TO GET THIS DONE. >> RACHEL, EVERY DAY IT CUTS THROUGH YOUR HEART. >> FOR US, IT'S OUR ONLY SON. AND IT IS AN INDESCRIBABLE TORMENT. >> Reporter: THE FAMILIES TELLING HOUSE MEMBERS TODAY -- >> WE MET PRIME MINISTER NETANYAHU AGAIN. I HAVE TO SAY, THE URGENCY OF THE MATTER DID NOT SEEM TO RESONATE WITH HIM. THE TIME IS NOW TO SIGN THIS DEAL. GET THE HOSTAGES HOME AND STOP THIS KILLING. >> Reporter: MEANWHILE, THE WAR GRINDS ON. ISRAEL'S MILITARY PUMMELLING SOUTHERN GAZA MONDAY. IN A SAFE ZONE IT SAYS TARGETING MILITANTS, BUT KILLING AT LEAST 70, INJURING 200, ACCORDING TO THE HAMAS-RUN HEALTH MINISTRY. THE PRIME MINISTER WILL MEET WITH PRESIDENT BIDEN THURSDAY AT THE WHITE HOUSE FOLLOWED BY BOTH BIDEN AND NETANYAHU HOLDING AN UNPRECEDENTED JOINT MEETING WITH THE HOSTAGE FAMILIES. AND FORMER PRESIDENT TRUMP, A NETANYAHU SUPPORTER, SAYS THE PRIME MINISTER IS COMING TO MAR-A-LAGO FRIDAY. >> ALL RIGHT, ANDREA MITCHELL, THANK YOU. >>> WE TURN TO THE TRAVEL NIGHTMARE WE'VE BEEN COVERING. DELTA AIRLINES NOW FACING A FEDERAL INVESTIGATION AS IT CANCELS HUNDREDS MORE FLIGHTS DAYS AFTER OTHER AIRLINES WERE RECOVERED FROM LAST WEEK'S GLOBAL COMPUTER MELTDOWN. HERE IS TOM COSTELLO. >> Reporter: DAY FIVE OF DELTA'S SUMMER MELTDOWN. >> WE'VE ALL BEEN WEARING THE SAME CLOTHES FOR TWO DAYS NOW. >> Reporter: PASSENGERS STILL STANDING IN HOURS' LONG LINES, SLEEPING ON AIRPORT FLOORS, ON TELEPHONE HOLD FOR NINE HOURS AND MORE, AND LUGGAGE PILED HIGH. 5400 FLIGHTS CANCELED SINCE FRIDAY MORNING. MOST AT CRITICAL DELTA HUBS AND AIRPORTS. >> WE ESTIMATE THIS HAS IMPACTED HUNDREDS OF THOUSANDS OF PASSENGERS, LIKELY MORE THAN HALF A MILLION. >> Reporter: NOW THE D.O.T. IS INVESTIGATING WHY DELTA DIDN'T RECOVER FROM FRIDAY'S COMPUTER CRASH AS QUICKLY AS OTHER AIRLINES, AND WHETHER IT'S PROVIDING REFUNDS, REBOOKING PASSENGERS AT NO ADDITIONAL COST, AND OFFERING FOOD AND HOTEL VOUCHERS. THAT COMPUTER CRASH CRIPPLED DELTA'S CREW SCHEDULING SYSTEM. >> DELTA CLEARLY HAS NOT BEEN ABLE TO RECOVER. AND THEY NEED TO TAKE CARE OF THEIR CUSTOMERS. I MADE THIS CLEAR DIRECTLY TO THEIR CEO. >> IN A STATEMENT TODAY, DELTA SAID ITS TEAMS ARE WORKING TIRELESSLY TO CARE FOR AND MAKE IT RIGHT FOR CUSTOMERS IMPACTED BY DELAYS AND CANCELLATIONS. THE AIRLINE, THOUGH, CANCELED ANOTHER 473 FLIGHTS TODAY, 13% OF ITS SCHEDULE. >> EVERY TIME WE GOT BOOKED OR REBOOKED, THAT FLIGHT GOT CANCELED. >> Reporter: THE MELTDOWN NOT AS SERIOUS AS SOUTHWEST'S WINTER 2022 MELTDOWN THAT AFFECTED MILLIONS OF PASSENGERS, FOR WHICH SOUTHWEST PAID A $140 MILLION FINE. THE D.O.T. WON'T SAY WHAT KIND OF FINE DELTA MIGHT HAVE TO PAY, BUT IT REMINDS PASSENGERS THEY'RE ENTITLED TO A FULL REFUND, NOT JUST A VOUCHER IF THEIR FLIGHTS ARE CANCELED. LESTER? >> OKAY, TOM, THANK YOU. >>> IN 60 SECONDS, A WHALE BREACHES A BOAT IN NEW ENGLAND. THE MOMENT YOU CAN'T MISS. >>> PLUS MIDDLEMEN ACCUSED OF INFLATING THE PRICE YOU PAY FOR PRESCRIPTION DRUGS. CONGRESS DEMANDING >>> YOU MAY WANT TO PAUSE FOR A SECOND AND TAKE IN THIS INCREDIBLE SCENE OFF THE NEW HAMPSHIRE COAST TODAY AS A WHALE CRASHED ON TO A SMALL BOAT, CAUSING TO IT CAPSIZE AND SENDING TWO FISHERMEN INTO THE OCEAN. THE WHOLE THING CAUGHT ON VIDEO BY THOSE IN A NEARBY BOAT. THE MEN IN THE WATER WERE RESCUED SAFELY. >>> WE'LL TAKE A TURN NOW TO PRESCRIPTION DRUGS AND THE EXECUTIVES BEHIND THE SCENES THAT YOU MAY NEVER EVEN HAVE HEARD OF WHO HAVE A MAJOR IMPACT IN THE PRICE YOU PAY FOR YOUR MEDICATIONS. ERIN McLAUGHLIN HAS OUR REPORT. >> DO YOU SOLEMNLY SWEAR OR AFFIRM -- >> Reporter: TONIGHT THE POWERFUL MIDDLEMEN MANAGING PRESCRIPTION DRUG ACCESS FOR MILLIONS OF AMERICANS GRILLED ON CAPITOL HILL. >> PEOPLE ARE DYING BECAUSE THEY CAN'T AFFORD THEIR MEDICATION, AND YOU ALL ARE PART OF THE PROBLEM. >> Reporter: PHARMACY BENEFIT MANAGERS, OR PBMs ARE RESPONSIBLE FOR NEGOTIATING PHARMACY PRICES WITH DRUG MANUFACTURERS. THEY'RE BEING ACCUSED OF PROFITING BY INFLATING DRUG COSTS AND SQUEEZING MAIN STREET PHARMACIES, IMPACTING PATIENTS. ONE SURVEY SHOWS NEARLY THREE IN TEN AMERICANS HAVE RATIONED OR SKIPPED DOSES OF PRESCRIBED MEDICINES DUE TO HIGH COSTS. >> YOU'RE SETTING DRAMATICALLY DIFFERENT PRICES FOR SOME MEDICATIONS ACROSS THE COUNTRY. >> IF YOU'RE NOT DELIVERING AN OUTCOME TO THE PEOPLE WHO USE IT, HOW LONG DO Y'ALL THINK YOU'RE GOING HAVE A JOB? >> Reporter: DURING THE HEATED AND COMPLICATED BIPARTISAN HEARING -- >> I FEEL LIKE THE MORE I HEAR, THE LESS I UNDERSTAND. >> Reporter: DEMOCRATIC CONGRESSMAN RO KHANNA POINTED TO THE CASE OF A 10-YEAR-OLD GIRL WHO HE SAYS NEEDED HUMIRA TO TREAT HER JUVENILE ARTHRITIS, BUT WAS DENIED FOR SIX MONTHS WHILE HER ARTHRITIS GOT WORSE. >> THEY WERE SAYING THAT THE DOCTOR NEEDED TO PRESCRIBE SOMETHING CHEAPER. CAN YOU MAKE A COMMITMENT TODAY THAT YOU'LL PRIVILEGE THE DOCTOR'S RECOMMENDATION OVER THE BUREAUCRACY'S RECOMMENDATION? >> AS A PHYSICIAN, I HOPE YOU UNDERSTAND THIS. WE VALUE OUR PARTNERSHIP WITH PHYSICIANS. >> Reporter: EXECUTIVES FROM THE THREE LARGEST PBMs RESPONSIBLE FOR MANAGING ACCESS TO NEARLY 80% OF ALL PRESCRIPTION DRUGS IN THE U.S. PUSHED BACK ON ALLEGATIONS THEY DRIVE UP PRICES. >> LAST YEAR ALONE, WE SAVED OUR CLIENTS $64 BILLION. >> Reporter: THEY BLAME BRAND MANUFACTURERS WHO THEY SAY RAISED DRUG COSTS UP TO 60%. >> IT'S HARD WORK TO KEEP THOSE COSTS DOWN FOR PATIENTS AND CLIENTS. >> Reporter: TONIGHT A GROUP OF BIPARTISAN LAWMAKERS HAS INTRODUCED LEGISLATION THEY SAY IS AIMED AT CRACKING DOWN ON PATIENT EXPLOITATION, ONE OF DOZENS OF EFFORTS TO REFORM PBMs AT THE FEDERAL AND STATE LEVEL. LESTER? >> ERIN McLAUGHLIN, THANK YOU. >>> UP NEXT FOR US HERE TONIGHT, THE SPECTACULAR EXPLOSION CAUGHT ON CAMERA AT YELLOWSTONE. >>> AND YOUNG DEMOCRATIC VOTERS WHO WERE DISMAYED BY THEIR OPTIONS SAY THE SHAKE-UP IN THE >>> AN ALARMING MOMENT CAUGHT ON CAMERA TODAY AT YELLOWSTONE NATIONAL PARK IN THE HEAT OF THE POPULAR TOURIST SEASON. A MASSIVE HYDROTHERMAL EXPLOSION SENT SENDING VISITORS RUNNING AT THE PARK'S POPULAR BISCUIT BASIN. THE ERUPTION CAUSING EXTENSIVE DAMAGE, BUT NO INJURIES. THAT SECTION OF THE PARK IS NOW TEMPORARILY CLOSED. >>> MORE NOW ON OUR TOP STORY, THE SEISMIC SHAKEUP IN THE 2024 RACE. BEFORE WITHDRAWING, PRESIDENT BIDEN WAS LOSING GROUND WITH YOUNGER VOTERS. ANTONIA HYLTON WENT TO A KEY BATTLEGROUND TO FIND OUT IF KAMALA HARRIS CAN WIN THEM BACK. >> Reporter: IN BATTLEGROUND MICHIGAN, YOUNG VOTERS ARE PROCESSING PRESIDENT JOE BIDEN'S HISTORIC DECISION TO EXIT THE RACE. ALREADY, MOMENTUM IS SHIFTING TO HIS VICE PRESIDENT, KAMALA HARRIS. >> I THINK SHE REALLY HAS AN OPPORTUNITY NOW TO REBRAND HERSELF AND INTRODUCE HERSELF TO THE COUNTRY IN A NEW WAY. >> Reporter: THESE GEN Zers ARE ALL DEMOCRATS AND HAVE NEVER HAD THE OPPORTUNITY TO VOTE FOR A PRESIDENT WHO WASN'T IN THEIR 70s OR 80s. WHAT DO YOU THINK IT IS ABOUT HER? >> WE KNOW THAT SHE IS A POWERHOUSE SPEAKER. >> SHE HAS A LEVEL OF AUTHENTICITY THAT YOU DON'T ALWAYS SEE FROM POLITICIANS. >> Reporter: FOR WEEKS, YOUNG PEOPLE HAVE BEEN SHARING MEMES ACROSS SOCIAL MEDIA, HIGHLIGHTING HARRIS' SPEECHES AND ACTIONS. ONE GEN Z FAVORITE -- >> YOU THINK YOU JUST FELL OUT OF A COCONUT TREE? >> Reporter: A MAY 2023 SPEECH IN WHICH HARRIS SHARED SOMETHING HER MOTHER USED TO SAY. >> YOU THINK YOU JUST FELL OUT OF A COCONUT TREE? YOU LINK THIS IN THE CONTEXT OF ALL IN WHICH YOU LIVE AND WHAT CAME BEFORE YOU. >> GROWING UP, I DIDN'T THINK AN INDIAN WOMAN LIKE ME COULD EVEN BE INVOLVED IN POLITICS. >> Reporter: THEY'RE WORRIED ABOUT REPRODUCTIVE RIGHTS, GUN CONTROL AND CLIMATE CHANGE. >> SHE HAS BEEN THE BIDEN CAMPAIGN'S MOST EFFECTIVE MESSENGER ON THE ISSUE OF ABORTION ACCESS AND REPRODUCTIVE FREEDOM. >> Reporter: BUT YOUNG PEOPLE HAVE BEEN UNSURE ABOUT BIDEN. IN MICHIGAN, A STATE WITH A LARGE MUSLIM POPULATION, MANY COMMUNITIES ARE OUTRAGED BY THE ISRAEL-HAMAS WAR AND GRATEFUL TO HARRIS, WHO HAS LONG PUSHED FOR A CEASEFIRE. >> THAT'S THE BARE MINIMUM THAT WE'VE BEEN ASKING FOR. AND I THINK THE MAIN ISSUE IS THAT WE'RE NOT SEEING ANY CHANGE. I THINK WE WILL STAY UNCOMMITTED UNTIL WE CAN BUILD TRUST. >> Reporter: A TUFTS UNIVERSITY STUDY FOUND MICHIGAN HAD THE HIGHEST YOUTH TURNOUT IN THE NATION IN 2022. >> I THINK THIS COUNTRY HAS A LONG HISTORY OF NOT REALLY LISTENING TO THE YOUNGER POPULATION. AND I THINK GEN Z IS AT A POINT WHERE WE'RE TIRED OF FEELING UNHEARD. >> Reporter: DO YOU THINK SHE IS STILL GOING TO HAVE TO FIGHT TO EARN THE YOUTH VOTE? >> OH, YEAH. >> Reporter: BUT FOR NOW THEY SAY SHE HAS BEEN ABLE TO BREATHE NEW LIFE INTO AN ELECTION THEY THOUGHT HAD GONE STALE. ANTONIA HYLTON, NBC NEWS, ANN ARBOR, MICHIGAN. >>> AND UP NEXT FOR US TONIGHT, ECHOES OF THE PAST. 100 YEARS LATER, THE PARIS OLYMPICS THEN AND NOW. >>> JUST THREE DAYS NOW UNTIL THE GAMES BEGIN. IT'S BEEN A CENTURY SINCE PARIS LAST HOSTED THE OLYMPICS. ANRTHEST. >> Reporter: THAT'S THE OLYMPIC SPIRIT? >> THAT'S RIGHT. >> Reporter: KEIR SIMMONS, NBC NEWS, PARIS. >>> THAT'S "NIGHTLY NEWS" FOR THIS TUESDAY. JOIN US TOMORROW NIGHT FOR OUR COVERAGE OF PRESIDENT BIDEN'S ADDRESS TO THE NATION AS HE EXITS THE 2024 PRESIDENTIAL RACE. COVERAGE BEGINS AT 8:00 P.M. THANKS FOR WATCHING, EVERYONE. I'M LESTER HOLT. PLEASE TAKE CARE OF YOURSELF AND EACH