Democrats swept Republicans from power in the House of Representatives and moved to within one seat of victory in the Senate today in a sharp rebuke of President George W. Bush that led immediately to Defense Secretary Donald Rumsfeld's resignation.
The move by Mr Rumsfeld followed huge Democratic gains in the US Congress in elections fueled by voter anger over the Iraq war and Mr Bush's leadership.
Democrats gained about 30 seats in the House in Tuesday's voting and picked up five of the six Republican Senate seats they need for a majority.
They led in the other one, Virginia, putting them near control of both chambers of Congress for the first time in 12 years.
Mr Bush said he was "obviously disappointed" in the election results. "The election has changed many things in Washington but it has not changed my fundamental responsibilities."
He said, however, that it was "time for new leadership" at the Pentagon.
"I recognise that many Americans voted last night to register there displeasure with the lack of progress being made there," he told reporters at the White House.
He added: "After a series of thoughtful conversations Donald Rumsfeld and I agreed that the timing is right for a new leadership at the Pentagon."
Mr Bush said his defence secretary had been a "superb leader" in his six years in the position. He named former CIA Director Robert Gates as his replacement.
Almost six in 10 voters disapproved of the war in Iraq, exit polls showed. Mr Bush conceded that his overall Republicans had taken a "thumping".
As to the role played in yesterday's widespread Republican losses, Mr Bush said: "I believe Iraq had a lot to do with the election, but I think there were other factors as well."
He suggested that a variety of congressional scandals may also have played a role.
A potential recount and possible legal challenges in Virginia could delay the final result, dredging up memories of the 2000 presidential election recount that lasted five weeks.
Virginia Democrat James Webb led Republican Senator George Allen by about 7,000 votes out of 2.3 million cast. The final vote counting could take a week, with a winner certified on November 27th and any recount stretching into December, leaving Senate control uncertain.
The Allen campaign indicated it did not plan to concede before the process ended. "We'll see where the official tally stands on November 27th and we'll come back and visit with you then," Allen adviser Ed Gillespie told reporters in Richmond, Virginia.
In Montana, Democrat Jon Tester was projected to narrowly beat Republican Senator Conrad Burns, although the possibility of a recount remained. The big Democratic victory, fueled by public discontent with the war in Iraq, corruption in Washington and Mr Bush's leadership, was likely to increase pressure for a change of course in Iraq.
Democratic leaders sought a summit with Mr Bush on Iraq's future. U.S. stock markets were trading slightly lower as investors took in the election results.
The split control of government and narrow majorities in Congress, especially the Senate, were almost certain to spawn more partisan gridlock and political warfare during Bush's final two years in the White House.
The Democratic victory gives the party control of House legislative committees that could investigate the Bush administration's most controversial decisions on foreign, military and energy policy.
Democratic control of the House will make outspoken liberal Democrat Nancy Pelosi of California the first female speaker and could slam the brakes on much of Mr Bush's agenda and increase pressure for a change of course in Iraq.
Mr Bush telephoned his congratulations to Pelosi and other Democratic leaders, pledging to work with them.
All 435 House seats, 33 of the 100 Senate seats and 36 of the 50 governorships were at stake. Democrats beat Republican Sen. Rick Santorum, the third-ranking Republican in the Senate and one of the Democrats' biggest targets this year.
Connecticut Sen. Joseph Lieberman, running as an independent, beat Democratic anti-war challenger Ned Lamont, who had defeated the former vice presidential nominee in the Democratic primary.
Democratic Sen. Hillary Rodham Clinton sailed to an easy re-election win in New York, setting up a likely 2008 presidential run. "This is a wake-up call to the Republican Party," said Republican Sen. John McCain of Arizona on CNN.
Democrats also scored big wins in governors' races, taking six seats from Republicans and winning a national majority that could give them an edge in the 2008 presidential election. In California, however, Republican Gov. Arnold Schwarzenegger won easy re-election.
In ballot initiatives on social issues, voters in seven states rejected same sex-marriage, providing one of the few bright spots for conservative Republicans in the elections.
Democrats have promised early votes on much of their legislative agenda, including new ethics rules, a rise in the minimum wage, reduced subsidies to the oil industry and improvements in border and port security.
Early exit polls showed voters disapproved of the war in Iraq by a large margin, but they said corruption and ethics were more important to their vote. Democrats hammered Republicans all year for spawning a "culture of corruption" in Washington, with four Republican House members resigning this year under an ethics cloud.
The party was hit by allegations about influence peddling, links to convicted lobbyists and a Capitol Hill sex scandal involving Republican Rep. Mark Foley's lewd messages to teenage male congressional assistants. The campaign-trail debate was dominated by Iraq, and Bush defended his handling of the war to the end despite job approval ratings mired in the mid-30s.
He questioned what Democrats would do differently and predicted Republicans would retain control of Congress. History was with the Democrats -- the party holding the White House traditionally loses seats in a president's sixth year.
Mr Rumsfeld, seen as the architect of the war in Iraq said the past six years had been "quite a time". Quoting Winston Churchill, he said: "I have benefited greatly from criticism and at no time have I suffered a lack thereof." He described the conflict in Iraq as a "little understood, unfamiliar war, the first war of the 21st century".
"It is not well-known, it was not well understood, it is complex for people to comprehend and I know with certain certainty that over time the contributions you've made will be recorded by history," he told Mr Bush.
The two men appeared together before the media, where they were joined by Mr Gates. He said he had not anticipated returning to government service but had not hesitated to accept the job because America was at war.