WASHINGTON, Oct 1, 2008 (AFP) - The next president of the United States on Wednesday voted to rescue Wall Street -- and in the process clamped a 700 billion dollar millstone to his own administration.

White House rivals John McCain and Barack Obama both rushed back from the campaign trail to vote in the Senate for the huge financial rescue package, which they both think is a bitter pill but nevertheless vital to saving the US economy.

Whichever one of them wins the election on November 4 will pay the price for the bailout and the economic crisis which spawned it, likely by having to pare back ambitious plans for tax cuts and government spending.

It was Democrat Obama, rising in the polls and buoyed by voter approval of his handling of the economic crisis, who appeared in the Senate first to deliver a lofty address, which morphed into a campaign speech.

Quoting former president Franklin D. Roosevelt, and implicitly tying himself to a man who inspired Americans out of a 1930s banking crisis with the power of his words, Obama said : 'Let us unite in banishing fear ... we cannot fail.'

'This is a nation that's faced down war and depression, great challenges and great threats.'

'And at each and every moment, we have risen up to meet these challenges, not as Democrats, not as Republicans, but as Americans, with resolve and with confidence.'

Surprisingly, Republican McCain, who has struggled to find his voice on the economic crisis, did not give a speech to the Senate, after suspending his campaign and throwing himself into bailout negotiations last week.

McCain swept into the chamber during a previous vote, flanked by a senatorial honor guard made up of Mel Martinez and John Thune, two of the tallest lawmakers on Capitol Hill.

It was Obama who broke the awkward tableau, crossing the floor of the Senate to offer his rival the briefest of handshakes -- there didn't seem to be much eye contact.

In another tricky moment, Obama offered a quick handshake to his vanquished Democratic primary rival Hillary Clinton, before they peeled off to talk to other senators.

Later however, Obama and Clinton were locked in deep conversation, punctuated at one stage by the former first lady's trademark cackle.

If the White House race was a Senate popularity contest there is little doubt that Obama would win.

The 47-year-old Illinois senator was constantly mobbed by his colleagues offering backslapping hugs. Some of the women senators offered their cheeks for a kiss.

Venerable Republican Senator Dick Lugar walked over to shake his hand, and at one stage another Republican Bob Corker fought his way through the throng to throw his arms around Obama.

McCain meanwhile stayed in the safety of the Republican benches chatting to other members, flanked by his campaign road buddies, Senators Lindsey Graham, Jon Kyl and Joseph Lieberman, who split with the Democratic Party over the Iraq war.

Democratic vice presidential nominee Joseph Biden also came back to vote -- and seemed to spend a long time in deep conversation with female senators -- possibly picking up tips for his debate with his Republican opposite number Sarah Palin on Thursday.