In a Washington landmark where her husband celebrated his 1996 White House re-election victory, Hillary Clinton will bow out of the Democratic presidential race today before thousands of supporters, millions of television viewers - and with her ambitions for the Oval Office still burning fiercely.

In the Grand Hall of the National Building Museum, just off Pennsylvania Avenue, Mrs Clinton will concede defeat to Barack Obama at noon and unequivocally call for party unity, even as she begins to plot the course of her political future.

The event, originally scheduled for yesterday, was moved so as not to coincide with the 40th anniversary of that assassination of Robert F. Kennedy.

Her concession follows a secret meeting with Mr Obama in Washington on Thursday night, when the two candidates - having given the press pack the slip - spent an hour alone together for what was described as a “positive and productive” encounter.

During an evening of cat and mouse that left the national media dashing around Washington in a fruitless search for the missing pair, the two met at the home of Dianne Feinstein, a fellow senator and supporter of the former First Lady, after Mrs Clinton initiated the tryst.

When Mr Obama was missing from his campaign plane after a campaign event in Virginia, suspicions were raised that a rendezvous with Mrs Clinton was afoot, sending reporters dashing to the former First Lady's Washington home.

In fact, at 9pm, Mrs Feinstein was ushering the two candidates into her living room with, she said, nothing other than water and two comfortable chairs.

“They talked. I went upstairs and did my work,” Mrs Feinstein said. “They called me when it was over. I came down and said, ‘Good night everybody, I hope you had a good meeting'. They were laughing and that was it.”

Aides to the two candidates waited in another room. All refused to comment on whether a possible vice-presidential slot for Mrs Clinton was discussed.

The two did discuss the tone of Mrs Clinton's message in her concession speech today. It is believed that Mr Obama was assured that it would have none of the defiance and divisiveness of her primary night address on Tuesday, when she refused to mention that her rival had passed the delegate threshold for the nomination, and hinted that she might prolong the fight.

In coming days and weeks, the candidates and their staff will discuss the details of how both Mrs Clinton and her husband, Bill, can help Mr Obama's bid. The Illinois senator said that he would welcome help from the former President, whom he called an “enormous talent”. The Obama campaign believes that Mrs Clinton will be an invaluable campaigner in swing states such as Pennsylvania and Ohio where she defeated Mr Obama heavily among white, working class voters, and women.

The two also discussed a joint appearance in the near future, a hugely symbolic moment that Mr Obama will be anxious to choreograph as he begins a quest to rally behind him the nearly 18 million Democrats who voted for Mrs Clinton. Many view him with deep antipathy. He spends this weekend at home in Chicago - to leave the spotlight on Mrs Clinton - where he says that he will take his wife on a date and go cycling with his two daughters.

As Mrs Clinton admits defeat, after a dinner tonight at her Washington home with campaign staff, she will have one eye on presidential candidates past - and the way they rose from the ashes of defeat - as she looks to her future.

The man she would most like to emulate is Ronald Reagan. On his second of three attempts to win his party's nomination, in 1976, he narrowly lost to the incumbent Republican President, Gerald Ford. But he won the hearts of the convention during a speech in which he cemented his credentials as the standard bearer for a resurgent conservatism. Mr Ford lost the election to Jimmy Carter, and Mr Reagan won the White House four years later.

“Of course she can't say it, but of course she hopes Obama loses [to John McCain],” said Larry Sabato, a political science professor at the University of Virginia. “It's akin to Reagan-Ford. If Obama loses in November, she can return in 2012 as the "I told you so' candidate.”

Richard Nixon also came back from twin defeats to win the presidency. He narrowly lost the White House race in 1960 to John F. Kennedy. In 1962 he was defeated in his attempt to win the California governorship, when he infamously and churlishly told reporters: “You won't have Nixon to kick around anymore, because, gentlemen, this is my last press conference.” It was a comment that made him look petty, bitter and unpresidential, and took him years to overcome, before he won the White House in 1968. Expect none of that from Mrs Clinton today.

Edward Kennedy took his 1980 primary fight against Jimmy Carter down to the wire, where, in finally conceding, he delivered one of the greatest convention speeches of recent times, his “The Cause Endures” address. He was gearing up for another White House run when, in 1983, his family intervened, believing the personal toll of him would be too great. Already a senior senator, having sat in the chamber since 1962, he has since transformed himself into a legislative “lion” on Capitol Hill.

Mrs Clinton, although a very powerful figure when she returns to the Senate, will struggle to emulate Mr Kennedy. There is no obvious route to becoming Majority Leader, and she is only 36th in seniority among the chamber's 49 Democrats.

If Mr Obama does win, and spends eight years in the White House, there is always 2016 - but when Mrs Clinton will be 69, a time when America might have long ago moved on from the House of Clinton.

Famous farewells

Charles I

Executed in 1649 after being found guilty of treason. Parting words: “I go from a corruptible to an incorruptible Crown, where no disturbance can be”

Richard Nixon

The only American president in history to resign, after the Watergate scandal. In 1974 he said he “regretted deeply an injuries that may have been done” and departed in a helicopter from the White House lawn

Margaret Thatcher

Resigned in 1990, after 11 years in power. Parting words: “I have concluded that the unity of the party and the prospects of victory in a general election would be better served if I stood down”

Mikhail Gorbachev

Announced his resignation in 1991, in a Christmas Day live televised speech. Parting words: “. . . as a result of the formation of the Commonwealth of Independent states, I hereby discontinue my activities at the post of president of the Union of Soviet Socialist Republics.”

Nelson Mandela

Ended his term as South Africa’s President in 1999. Parting words: “For my part, I would like to say how privileged I feel to have participated in the achievements of our nation during the past five years. I have been humbled . . . It has been an inspiration”

Sources: www.info.gov.za; Times archives

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