By Justin Webb
BBC News, Washington
Senator Charles Schumer - one of the organisers of the Democratic effort this year - tried to keep his troops' feet on the ground as results rolled in. But as the night wore on it got more difficult.
"We're not breaking out the champagne bottles yet," he said when he spoke before cheering supporters at the Democrats' victory celebration in Washington.
Democrats sensed their victories early on
But by the time Hillary Clinton crushed her opponent in New York state to win another term in the Senate, there was a real sense among Democrats that they had broken through.
"When I return to Washington next week, I do so knowing that we have made a statement here tonight, that we believe in who we are as a state and we believe in our country," Senator Clinton said.
"And we are going to take it back starting tonight, so to all of you - thank you, God bless you, God bless New York and God bless America."
'Change on Iraq'
Moments after Mrs Clinton spoke, her boss Harry Reid - the Democratic leader in the Senate - summed up what the victory in the House of Representatives would mean.
"All over America tonight they have come to the conclusion - as we did some time ago - that a one-party town just simply doesn't work," he said.
Nancy Pelosi stands to be the first woman speaker of the House
"America has come to the conclusion - as we did months ago - that we must change direction in Iraq."
Again and again Democrats have been mentioning Iraq and mentioning change.
Nancy Pelosi, who looks likely to become the new Speaker of the House of Representatives, said the current path had been catastrophic.
But she made it clear that she would be looking for solutions, not scalps.
"Democrats are ready to lead," she said. "We are prepared to govern and we will do so working together with the administration and the Republicans in Congress in partnership - not in partisanship."
New powers for Democrats
For President Bush, the loss of the House of Representatives is a big blow.
He will speak later on Wednesday, but Republican Party chairman Ken Mehlman has already appeared to suggest that some element of bipartisan compromise was on the cards once the dust had settled.
"I think what we've got to do is to continue to work, recommit ourselves to the principles we believe in, and try to work in a bipartisan basis to accomplish those principles," he said.
The Democrats were euphoric at the results
For the White House, the bleak fact is that majority status in the House of Representatives gives the Democrats the chairmanship of every committee - giving them the power to hold hearings and the power to initiate legislation.
What will they do with that platform?
Will they try, for instance, to impeach the president? Or will they stick to Ms Pelosi's stated goal of leadership?
Probably the latter. Many of the new intake are moderate Democrats, conservatives even, who are not looking for an ideological fight.
'Looking for leaders'
One of the stars of the Democratic firmament, the mixed-race Senator Barack Obama, put it like this:
"The critical message in this election is going to be that the American people are in a serious mood.
"They recognise the challenges that we face, and they are hopeful that the Democrats can provide some leadership that's been lacking from the other side, both in Congress and the White House."
Meanwhile, what of the Senate?
Incredibly, we do not know who is going to be in control.
It will probably come down to one state - Virginia - where recounts and litigation could go on for weeks.