The electoral storm sweeping around George Bush has rewarded moderate Democrats and made the Republicans more conservative than ever, writes Denis Staunton.
When it came, the storm that hit Congress was a Category five hurricane that not only swept dozens of Republicans from office but wrecked the strategy that helped the party win elections since 1994.
For president George Bush, it was, as he acknowledged last night "a thumping" but it was above all a clear and damning verdict on his military adventure in Iraq.
The president's first response to the Democratic victory was to announce the departure of Donald Rumsfeld as defence secretary, a move that will please critics in both parties and in the armed forces who blame Mr Rumsfeld's arrogance for much that has gone wrong in Iraq.
Less than a week ago, Mr Bush said that the defence secretary would remain in his job until 2009 but the president admitted yesterday that he was already considering a change at the Pentagon when he made that statement. In the final days of the campaign, numerous Republican candidates were calling for Mr Rumsfeld to go and senior military commanders had long ago lost confidence in their civilian leadership.
"He himself understands that Iraq isn't working well enough or fast enough," the president said of Mr Rumsfeld yesterday. Mr Bush's choice as the new defence secretary, former CIA director Robert Gates, is a member of the Iraq Study Group, a bipartisan committee charged with coming up with a new US policy on Iraq. The committee, which is chaired by former secretary of state James Baker and former congressman Lee Hamilton, is considering ideas that have long been anathema to the administration, such as involving Syria and Iran in plans for Iraq's future.
Mr Bush promised yesterday to work with the Iraq Study Group and the new Democratic leadership in Congress to agree an approach to Iraq. He signalled that important changes were on the way at the Pentagon.
"There's certainly going to be new leadership. Bob Gates will bring a fresh perspective," Mr Bush said.
For the Democrats, a change of policy in Iraq is essential if the party is to fulfil the mandate it received at the polls on Tuesday. Nancy Pelosi, who is set to become the first woman Speaker of the House of Representatives, said yesterday that the election was a clear call for a new direction on Iraq.
"It's not about the Democrats in Congress forcing the president's hand. It's important for us to work in a bipartisan way with the president, again, to solve the problem, not to stay the course," she said.
Despite the Democrats' comfortable margin of victory in the House, Ms Pelosi is likely to keep her promise to embrace bipartisanship, not least because it may be the best way to preserve a Democratic majority in 2008. Many of the new Democratic intake are moderates from districts long held by Republicans who will resist any attempt to push through radical measures that appeal to the left-wing, Democratic base.
The president has already suggested that he can work with Democrats on issues like education and increasing the minimum wage and a Democratic-run Congress could also work with Mr Bush to pass comprehensive immigration reform.
One of the most dramatic features of Tuesday's election was the collapse of Hispanic support for the Republican Party, which has been wooing that socially conservative community for more than a decade. Exit polls showed Hispanics favouring Democrats by 72 per cent to 27 per cent, almost certainly on account of many Republican candidates' hardline stance on immigration.
If the new Democratic intake is more moderate, the remaining Republicans in Congress are more conservative than ever, with leading moderates such as senators Lincoln Chafee and Mike DeWine losing their seats. Moderate Republicans in the northeast took the brunt of the Democratic onslaught, leaving the Republican Party more firmly anchored in the conservative south.
Republicans in the west paid a price for abandoning the political centre, with a prominent anti-immigration candidate, Randy Graff, losing to a pro-immigrant Democrat in Arizona - which also became the first state to reject a gay marriage ban.
Senator John McCain's presidential ambitions could benefit if Republicans conclude that they need a candidate who can reach beyond the party's base to independents and moderate Democrats.
The shift of power this week that saw Democrats take a majority of state governorships could benefit the Democratic presidential candidate in 2008, bringing into play states that were until now strongly Republican.
Senator Hillary Clinton's sweeping victory in New York, which may also have helped Democrats to pick up congressional seats in the state, can only help her presidential ambitions if she chooses to run. Former president Bill Clinton's energetic fundraising and campaigning on behalf of Democratic candidates has helped to secure the loyalty of party officials throughout the country.
Many of the new Democratic congressmen and senators embrace an economic populism, with opposition to free trade and an emphasis on labour rights that is at odds with the Clintons' pro-business approach. Former vice-presidential candidate John Edwards could become the standard-bearer for the new Democratic populists in 2008, while Illinois senator Barack Obama's presidential appeal has grown during the recent campaign.
As Democrats prepare to move into their new leadership offices in January and Republicans are braced for a bitter round of infighting and recriminations, the US public will have little time to catch its breath before the campaigning starts again for the big prize in 2008.