By Richard Allen Greene
BBC News, Washington
Washington has hardly swept up the confetti and empty bottles left over from the celebrations and commiserations of Election Day 2006, but the race for the White House two years from now has already begun.
George W Bush is barred by law from seeking a third term, and Vice-President Dick Cheney has said he will not stand, so officially, the field is unusually wide open.
Mr McCain will benefit keeping his distance from President Bush
But in fact, each party has a clear front-runner: John McCain for the Republicans and Hillary Clinton for the Democrats.
Both already have organisations in place and are raising funds, and both have reason to smile after the 2006 results.
Sen McCain - although he is a Republican - is perhaps the biggest beneficiary of the voters' swing against
President Bush, since he has staked out a clear contrast between himself and the president, political scientist Larry Sabato says.
"It's obvious that a Bush look-alike will have great trouble winning in 2008," says Mr Sabato, the director of the University of Virginia Center for Politics.
Mr McCain also worked hard this year, although he was not up for re-election himself, Mr Sabato adds.
"He got around. He helped other candidates raise money, but he also raised money for himself and got commitments from people."
That's true too of Mrs Clinton, at least in the fund-raising stakes.
Facing an opponent whom no-one doubted she could beat, she banked enormous sums, finishing the campaign with twice as many votes as her rival - and $20m left over.
Hillary Clinton came out of 2006 with $20m in the bank
Her victory speech was "presidential in style", Mr Sabato says, but he does not rate her 2008 chances overly highly.
"She doesn't have charisma. She is a wooden public speaker, giving a pedestrian address on election night," he said.
He is not the only one with his doubts about the former first lady. Many Democrats fear she is too divisive a figure ever to win a national election.
Many Republicans, meanwhile, have their doubts about Mr McCain, either because he has opposed the president on high-profile issues or because they do not think he is sufficiently conservative on social values.
'Anybody but ...'
So for many in each party, the question now is: If not the front-runner, then who?
Several men who had been positioning themselves as conservative alternatives to Mr McCain had bad nights as 2006 results came in.
Mitt Romney, the outgoing governor of Massachusetts, had chaired the Republican Governors' Association.
George Allen sank his campaign with an insensitive comment
His party lost six governors' mansions - including Mr Romney's own.
"He was in charge of millions of dollars which went to losing candidates, and there was a massive landslide against his lieutenant governor," Mr Sabato points out.
The outgoing governor of Arkansas, Mike Huckabee, also failed to keep his job in Republican hands.
Senator Sam Brownback of Kansas saw the Democrats make strong gains in his conservative state, casting doubt on his campaigning abilities.
But the Republican who self-destructed most dramatically was Senator George Allen of Virginia.
Considered a strong candidate for the Republican nomination to the presidency only three months ago, he ended up losing his own re-election battle after a comment seen as racially insensitive.
Across the aisle, Democratic Senator John Kerry - the loser in 2004 - may well also have destroyed any lingering presidential chances this year.
He made a comment which the Republicans portrayed as an insult to the US military, and although he insisted it was a botched joke aimed at President Bush, it would be dangerous ammunition against him if he ran for president again.
Mr Kerry's botched joke would come back to haunt him
Many other Democrats will expect their chances to have been boosted by the party's storming into control of both the House and Senate for the first time in more than a decade.
Senator Joseph Biden is in line to become chair of the Senate Foreign Relations committee, giving him a platform to look presidential as he seeks a bipartisan solution to the Iraq imbroglio.
Senator Evan Bayh helped the Democrats to pick up three House seats in his conservative state of Indiana, reinforcing his image as a vote-winner in Republican territory.
And Senator Barack Obama's stock continues to rise and rise.
Adoring crowds turned out to cheer for him as he campaigned on behalf of candidates such as Jim Webb, who captured George Allen's Virginia Senate seat.
Not everyone is convinced of America's willingness to elect a black man to the White House, but elections expert David Bositis thinks Mr Obama can overcome any lingering prejudice.
Barack Obama: "Rock-star" reception
He concedes that Harold Ford, the season's highest-profile African-American candidate, lost a Senate race in Tennessee, but observes that Mr Ford took 40% of the white vote in a Southern state.
"That might not sound like a lot, but it is," says Mr Bositis, of the Joint Center for Political and Economic Studies.
And he says the Republicans could never run the kind of negative commercial against Mr Obama that they ran against Mr Ford, which played to racist fears of mixed-race sexual relations.
"Obama is the perfect family man, with a beautiful wife and children straight out of the Saturday Evening Post", the home of Norman Rockwell's idealised images of Middle America.
He thinks the Democrats as a party boosted their chances of winning in 2008 on election night in 2006.
"They were winning big in some places where they had not in the past. In the overall landscape, Obama probably saw quite a bit to like. All the Democrats would be smiling."
But Larry Sabato is more cautious.
"The Democrats have the image of being winners now, but you can lose by winning. If the wingnuts [crazies] take over, voters may decide to check the Democratic Congress with a Republican president in 2008."