While the battle for the US Senate still hangs in the balance, Democrats have won at least the net 15 seats needed to take the House of Representatives for the first time since 1994.
This means Democrats can now appoint House committee chairmen that will set the legislative agenda for the next two years, including trade policies, and the power to conduct inquiries into the conduct of the Bush administration's policies.
The implications for President Bush efforts to push thorough its agenda are significant irrespective of whether the Republicans hold the Senate. Even if the Democrats take control their slim majority - propped up by two independents - will only give them limited power in the upper house.
Many commentators are already predicting Congressional gridlock with in-fighting among left and right wings of the Democrats presenting a problem for the ultra-liberal House leader Nancy Pelosi.
US AND INTERNATIONAL EXPERTS
Joseph Aistrup, Professor of Political Science, Kansas State University:"The war in Iraq and concerns about President Bush's leadership seem to be providing the undercurrent for the results we're seeing ."
David Bositis, political analyst with the Joint Centre For Political and Economic Studies:"It's a rejection of George Bush. Right now the Republican Party is a southern party and if they are going to just be a southern party they are going to be a minority party."
Alexander Lamis, Professor of Political Science, Case Western Reserve University, Cleveland:"It's going to change the political dynamic in Washington in a dramatic way. The House of Representatives will now begin to challenge the president and Democrats will have leadership positions in all the key committees and there is a lot you can do when you control the committees and the majority in the house.
It does mean we will have deadlock on the big policy areas, but it's going to be a difficult time for President Bush unless he compromises with this new majority in the House."
Michael Mckinley, International Relations Specialist From Australian National University:"I think it's being over read to be honest. We're two years away from a presidential election. The President remains the Commander in Chief, his administration remains there, and he can appeal to the fear factor and to the support our troops factor.
"If the United States withdraws from Iraq in the current situation, that would be a defeat of Vietnam proportions, and it would be understood as such.
Satoshi Morimoto, Former Japanese Diplomat:" I don't think we have serious implications for the US-Japan alliance. But hypothetically, if the US budget for the Iraq operation is cut by the House, the US may shrink its presence in Iraq and that would be associated with our operation in Iraq."
Salman Haidar, former Indian Foreign Secretary:"It is not going to make that much of a difference to American policy to South Asia. In the Middle East there may be a stronger reaction in terms of reassessing the nature and duration of American commitment.
Matt Foreman, executive director of the National Gay And Lesbian Taskforce:"I would say that it is clear that fear-mongering around same-sex marriage by the Republicans and the extreme Christian Right is fizzling. It just doesn't have the juice it had two years ago. People are getting sick of it."
Stephen Leong, assistant director general, Institute Of Strategic And International Studies, Malaysia:"From the Southeast Asian point of view, this is a positive development in the sense that hopefully the Democrats will have a more constructive approach to the war on terror with less emphasis on military intervention and more on soliciting views and working with the international community.
Lee Dong-Bok, fellow of the Csis Think-Tank, expert on North Korean Negotiating Tactics:"A Democratic win probably won't have an impact on the [North Korean] nuclear issue, because in many ways the Democrats have taken a harder line [than the Republicans] when it comes to the nuclear problem. We have seen the Democrats saying there should be a give and take, and, if the North isn't forthcoming, then force may have to be used.