WASHINGTON — Hillary Rodham Clinton will end her presidential campaign Saturday at an event in Washington.

She will thank supporters and formally endorse rival Barack Obama, who clinched the nomination on Tuesday.

The campaign said in a statement Friday that the event will take place at noon (11 a.m. Austin time) at the National Building Museum.

The former first lady is expected to urge Democrats to unite behind Obama and help him defeat Republican John McCain in November.

Clinton and Obama met privately at the home of California Sen. Dianne Feinstein Thursday night to discuss the campaign going forward.

One of her top supporters, fellow New York senator Charles Schumer, said Friday that Clinton would accept the No. 2 spot.

"She has said if Senator Obama should want her to be vice president and thinks it would be best for the ticket, she will serve, she will accept that. But on the other hand, if he chooses someone else she will work just as hard for the party in November," Schumer, Clinton's New York colleague in the Senate, told ABC's "Good Morning America."

Clinton and Obama met in Washington Thursday night, going to great lengths to keep the meeting secret from the media beforehand. Schumer said the meeting was not about the vice presidency.

Robert Gibbs, an Obama spokesman, said the meeting was to talk about uniting the Democratic Party.

"Senator Obama and Senator Clinton did have occasion to meet this evening," Gibbs said late Thursday. "It's the end of the primary process. They wanted to talk about bringing these campaigns together in unity."

The Senate Majority Leader Harry Reid, who had remained uncommitted throughout the primaries, endorsed Obama Friday.

Obama is "a once-in-a-generation leader who connects with the hopes and dreams of the American people and will deliver the long-overdue change that our country desperately needs," the Nevada Democrat said in a statement.

Gibbs would not say where the former rivals met, except that it was not at Clinton's home in Washington, as had been widely reported. CNN reported Friday that the meeting was at California Sen. Dianne Feinstein's home.

Reporters traveling with Obama sensed something might be happening between the pair when they arrived at his campaign plane after an event in Northern Virginia and he was not aboard.

Asked at the time about the Illinois senator's whereabouts, Gibbs smiled and declined to comment.

Clinton spokesman Howard Wolfson said the former first lady isn't waging a campaign for No. 2.

"She is not seeking the vice presidency, and no one speaks for her but her," Wolfson said Thursday. "The choice here is Senator Obama's and his alone."

Obama on Tuesday night earned the 2,118 delegates he needed to secure the Democratic nomination.