WASHINGTON - Hillary Rodham Clinton met late Thursday with Barack Obama, a day after saying she would end her quest for the Democratic nomination and endorse the Illinois senator. A senior Obama campaign official confirmed to NBC News that Obama delayed his departure from Washington Thursday night to meet with Clinton at her home here. Earlier, Clinton had disavowed efforts by some supporters who have urged Obama to choose her as his running mate. "She is not seeking the vice presidency, and no one speaks for her but her," communications director Howard Wolfson said. "The choice here is Senator Obama's and his alone." Clinton was planning an event in Washington Saturday to thank supporters and urge them to back Obama's candidacy. But as she was bowing out of the race, supporters in Congress and elsewhere were ramping up a campaign to pressure him to put her on the ticket in the No. 2 spot. Bob Johnson, the billionaire founder of Black Entertainment Television and a Clinton supporter, sent a letter to the Congressional Black Caucus Wednesday urging the group to encourage Obama to choose Clinton as his vice presidential pick. He said he was doing so with her blessing. Obama is seeking to become the first black president. Clinton has told other friends and supporters she would be willing to be Obama's running mate. But her immediate task is bringing her own presidential bid to a close. High stakes In an e-mail to supporters, the New York senator said she "will be speaking on Saturday about how together we can rally the party behind Senator Obama. The stakes are too high and the task before us too important to do otherwise." Clinton expressed the same sentiment in a conference call with 40 members of her national finance committee, whom she urged to begin raising money for Obama and for the Democratic National Committee. "She was in good spirits and totally supportive, without qualification, of Senator Obama and his campaign," finance co-chairman Alan Patricof said of the call. It was a shift in tone by the former first lady, who announced 17 months ago that she was "in it to win it." Many of her supporters want her as the vice presidential candidate, in their minds a "dream ticket" that would bring Obama her enthusiastic legions and broaden his appeal to white and working-class voters. But Obama indicated he intends to take his time making a decision. "We're not going to be rushed into it. I don't think Senator Clinton expects a quick decision and I don't even know that she's necessarily interested in that," Obama told NBC in an interview. Clinton's move to formally declare that she is backing the Illinois senator came after Democratic congressional colleagues made clear they had no stomach for a protracted intraparty battle. Now that Obama has secured the 2,118 delegates necessary to clinch the nomination, Clinton had little choice but to end her quest, and sooner rather than later. Some of Clinton's closest supporters — the nearly two dozen House Democrats from her home state of New York — switched their endorsements to Obama Thursday. The public announcement from the 23 New York followed two days of private phone calls weighing her options. "She was just as spunky as ever," Rep. Charlie Rangel said of Clinton's mood on the calls, as her friends and supporters urged her to come to a decision "sooner rather than later." Many of the lawmakers said it was important for them, as New Yorkers who are close to Clinton and helped launch her presidential bid, to work together to repair some of the rifts in the party. "We're Democrats. Dammit to hell we fight. When it's over, we come together and go out there to win," said Rangel, the dean of the New York delegation. The New Yorkers, said Rep. Gregory Meeks, have a duty "to lead this transition" to full party support of Obama. Another of Clinton's most prominent supporters, Ohio Gov. Ted Strickland, also announced his "wholehearted and enthusiastic support" for Obama Thursday. Exit strategy The move to end her campaign came Tuesday, when Clinton told House Democrats during a private conference call that she would get behind Obama's candidacy and congratulate him for gathering the necessary delegates to be the party's nominee. The only degree of uncertainty was how. Clinton is exploring options to retain her delegates and promote her issues, including a signature call for universal health care. The announcement closed an epic five-month nominating battle pitting the first serious female candidate against the most viable black contender ever. Obama on Tuesday night secured the delegates needed to clinch the Democratic nomination. But Clinton stopped short of acknowledging that milestone, defiantly insisting she was better positioned to defeat McCain in November. "What does Hillary want? What does she want?" Clinton asked, hours after telling supporters she'd be open to joining Obama as his vice presidential running mate. But by Wednesday, other Democrats made it abundantly clear they wanted something too: a swift end to the often bitter nominating contest. Her decision to acquiesce caught many in her campaign by surprise and left them scrambling to finalize the logistics and specifics behind her campaign departure.