|Projected balance of power in the 435-member House of Representatives, not including 13 undecided seats
Opposition Republicans have scored major victories in the country's midterm elections by taking control of the House of Representatives from the Democrats and scoring impressive gains in the Senate.
On Tuesday, Republicans captured 60 seats formerly held by Democrats in the House, exceeding the 39 needed to gain a majority. Meanwhile, Democrats picked up only two seats from the conservative party.
Following the poll victory, Republican Congressman John Boehner was designated to replace Nancy Pelosi as the speaker of the US House of Representatives.
He said the election results were a signal of a growing movement against the ruling administration's policies.
"Across the country right now, we are witnessing a repudiation of Washington, a repudiation of big government, and a repudiation of politicians who refuse to listen to the people,'' Boehner said.
"But we must remember it is the president who sets the agenda for our government. The American people have sent an unmistakable message to him tonight, and that message is: change course.
"We hope President Obama will now respect the will of the people, change course and to commit to making changes that they are demanding."
| Patty Culhane reports on how the economy has been a dominant issue in US elections
Obama called Boehner to congratulate him and said he looked forward to working with him and the Republicans "to find common ground, move the country forward and get things done for the American people,'' the White House said.
Boehner told the president that he wanted to collaborate on voters' top priorities by creating jobs and cutting government spending.
Republicans have also made big gains in the Senate, capturing a net of six seats from Democrats.
But the party fell short of the 10 needed to gain control of the upper legislative chamber.
Republican congressman Mark Kirk has narrowly defeated state treasurer Alexi Giannoulias to win the Illinois Senate seat, which was held by Obama before his 2008 presidential election.
Three-term Democrat Russ Feingold of Wisconsin lost his Senate seat to Republican Ronald Johnson - a significant blow to the more liberal wing of the President's party.
Republican Patrick Toomey defeated Joe Sestak for Republican-turned-Democrat Arlen Specter's seat. Dan Coats, a former ambassador to Germany, won an Indiana seat from the Democrats.
John Hoeven, North Dakota's Republican governor, won the Senate race there, taking a Democratic seat. And John Boozman has unseated the Democratic candidate in Arkansas.
But Democrats held on to their Senate majority by winning key races in Nevada, West Virginia, and California.
Democrats won the biggest single race in Nevada, with Senate Majority Leader Harry Reid defeating Sharron Angle, a favourite of the Tea Party movement.
|The new 100-member Senate, not including 2 undecided seats and 2 independents who caucus with the Democrats
Rand Paul, a Senate candidate also backed by the conservative Tea Party movement, won in Kentucky.
Senate races in Washington and Alaska are still too close to call.
Republicans managed to capture Democratic governorships in at
least 10 states on Tuesday, including some in prime presidential battlegrounds.
These states include Pennsylvania, Ohio, Michigan, Wisconsin, Iowa, Tennessee, Kansas, Oklahoma, New Mexico and Wyoming.
The mid-term elections also produced historic results for minority candidates.
In New Mexico, Susana Martinez was elected as the nation's first female Hispanic governor.
Nikki Haley, whose parents were born in India, will be the first female governor in South Carolina as she replaces Mark Sanford, and Brian Sandoval became Nevada's first Hispanic governor.
On the Democratic side, Terri Sewell became the first African-American woman elected to congress in Alabama.
Opposition to President Barack Obama's agenda fuelled the Republican surge, and many also connected Obama to the rise of minority Republican candidates.
14 black Republicans were on House ballots nationwide, almost double the number in 2008.
"Colour is becoming less of an issue,'' said Richard Ivory, a black Republican political consultant and founder of the website hiphoprepublican.com.
"There was a time when the white electorate saw race first and made judgements based on this alone. While black Republicans and Obama disagree ideologically, both are candidates whose message surpassed pigment.''
Mark Sawyer, a UCLA professor and director of the university's Center for the Study of Race, Ethnicity and Politics, said Obama's election pushed the Republicans to adjust to a more diverse electorate by seeking out minority candidates.
But he noted that almost all the victorious Republican minorities were elected in majority-white areas and opposed measures such as comprehensive immigration reform that are favoured by many Latinos and blacks.
"This election does not show a substantive embrace of a minority agenda,'' Sawyer said.
Assessing the results
A Republican victory in either chamber would usher in a new era of divided government, complicate Obama's ability to enact his proposals during the next two years and possibly force him to fight off attacks on health care legislation and other bills already signed into law.
Though international affairs had little role in the campaign, Obama's global agenda also would be affected in areas such as arms control and climate change.
Before the first results came in, Washington already was buzzing with speculation about whether Republican gains would lead to gridlock or attempts to find common ground, and how they would affect Obama's prospects for re-election in 2012.
In addition to the congressional vote, Republicans were expected to make gains in the 37 governors' races and state legislature campaigns, both especially important as states conduct the once-a-decade task of redrawing congressional districts.
The elections were the biggest test yet for the Tea Party movement, an amorphous series of groups angered by what they see as the excessive growth of government.
A big Republican victory signals a stunning turnaround in American politics since Obama won the presidency two years ago campaigning on a message of hope and change.
Although the president was not on the ballot, Obama's presidency was at the heart of many campaigns. His popularity has fallen, and Republicans have capitalised on frustration with the weak economic recovery, high unemployment and rising federal deficit.
Four in 10 voters said they are worse off financially than they were two years ago, according to preliminary exit poll results and pre-election polls.
Those who cast ballots expressed dissatisfaction with Obama as well as the two political parties. Democrats blamed the policies of Obama's predecessor, Republican George W Bush, for the weak economy and said Obama's policies prevented a financial catastrophe.
It was difficult to campaign on the message that things could have been worse.
Independents and other voters who had supported Democrats in 2008 shifted to Republicans.
"I will honestly say that I voted for him two years ago," said Sally McCabe, of Plymouth, Minnesota. "And I want my vote back."
Al Jazeera's Rob Reynolds, reporting from Washington DC, said that voters were sending a strong message by supporting Republicans in the mid-term poll.
"The message that was sent by the voters is that they were not nearly satisfied with what the Democrats and Obama had done over the past two years. Because the Democrats had controlled the White House and the Senate, the only way that discontented voters could send a message about the economy, concerns over joblessness, deficits, and government spending was through a vote for Republicans," he said.
"We're going to have divided government for the next two years. The impact is that it will affect Obama's ability move forward with legislation and to particularly implement his domestic agenda."
Obama gave a series of radio interviews pleading with Democratic supporters not to sit on the sidelines.
"I know things are still tough out there, but we finally have job growth again," he said in one.
All 435 seats in the House were on the ballot, plus 37 in the Senate.
Despite the anti-establishment mood, most incumbents were expected to be re-elected. But 100 House races were seen as competitive, an astonishing number by American standards.
About half those seats were in districts Republicans lost to Democrats in 2006 and 2008.
US Midterm Elections 2010