CBS News is projecting that when all the races are determined, the Republicans will control the House but Democrats will maintain control of the Senate.
Republicans needed 10 gains in the Senate to win control, but as of early Wednesday morning, they had only won six. CBS News cannot yet project a winner in Colorado, Washington or Alaska because these races are still too close to call. On the House side, Republicans had picked up 58 seats as of early Wednesday, with several left to be counted.
, CBS projects, after a dramatic battle against Tea Party-backed Republican Sharron Angle. Democratic Sen. Barbara Boxer of California is also Republican challenger Carly Fiorina, though the Republican refused to concede late Tuesday night.
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The GOP was able to pick up a Senate seat in Pennsylvania, where CBS projects Republican Pat Toomey will prevail over Democratic Rep. Joe Sestak. In Illinois -- in the battle for President Obama's old Senate seat -- over Democrat Alexi Giannoulias.
CBS News further estimates that when all the votes are counted, Democrat Daniel Inouye will win the Hawaii Senate race.
In the House, Republicans have picked up well past the 39 seats needed to win the majority. The new balance of power will present a challenge for Mr. Obama as he attempts to continue with his agenda through the second half of his term, and it will give voters renewed expectations for progress in Washington.
Republicans won a meaningful House victory early on in the evening in Virginia, where Republican Robert Hurt won the race for the state's fifth district. At 8:30, Hurt led Democratic incumbent Tom Perriello 52 percent to 46 percent. Perriello ran unabashedly on his record of supporting President Obama's agenda, and his re-election bid was considered something of an indicator as to whether the Obama supporters who voted in 2008 would mobilize again this year.
The GOP's strategy this year was to pick off Democrats elected in 2006 and 2008 to put their victory together, according to CBS News Capital Hill correspondent Nancy Cordes. Along with Perriello, freshman Democratic Rep. Alan Grayson lost in Forida's eighth district to Republican Daniel Webster.
Republicans also picked up a House seat in Indiana's ninth district, where Republican Todd Young defeated Democratic incumbent Baron Hill.
House Republican Leader John Boehner of Ohio, presumably the next speaker of the House, conducted a Skype call with Tea Party activists in his district tonight. "I'll never let you down," Boehner told the crowd in signing off.
Mr. Obama, meanwhile, called Boehner on Tuesday night, along with Democratic House Speaker Nancy Pelosi, House Majority Leader Steny Hoyer and Senate Republican Leader Mitch McConnell.
In his calls with Boehner and McConnell, the president said he was "looking forward to working with him and the Republicans to find common ground, move the country forward and get things done for the American people."
Rep. Mike Pence, chair of the House Republican Conference, said this election gives Republicans a "second chance."
"This election victory belongs to millions of Americans who stood up, spoke out and said 'enough is enough' and would no longer tolerate an imperial Congress that ignored the will of the people," he said in a statement. "House Republicans will welcome our new generation of leaders with open arms and work every day to deserve the confidence the American people have placed in us."
GOP House Win "Slap in the Face" for White House
House Republican Whip Eric Cantor that he hopes to see a repeal of the president's health care reform package go to the floor under Republican control.
On the Senate side, Democrats took a beating in Wisconsin, where incumbent Democrat Russ Feingold to Republican Ron Johnson. In another critical Senate race in Missouri, Republican Roy Blunt defeated Democrat Robin Carnahan. Republican David Vitter of Louisiana held onto his Senate seat.
"Tonight the American peolple are repudiating Barack Obama's policies," Mississippi Gov. Haley Barbour, chair of the Republican Governors Association, said on the CBS News Election Night Special.
President Obama was not expected to make any statements until a news conference Wednesday. "We expect a lot of words about compromise from the White House tomorrow," said CBS News chief White House correspondent Chip Reid.
Republican Marco Rubio's victory in the Florida Senate race, along with Rand Paul's victory in the Kentucky Senate race, delivered the Tea Party movement two resounding wins on Election Night.
In Delaware, however, Democrat Chris Coons Republican Tea Party favorite Christine O'Donnell. And in the closely-fought Senate contest in West Virginia, defeated Republican John Raese.
The GOP also pulled off a victory in the New Hampshire Senate race with candidate Kelly Ayotte. Republican Rob Portman won the Ohio Senate race, Republican Richard Burr won the North Carolina Senate race, and Republican Dan Coats won the Indiana Senate race.
Republicans also picked up a seat in North Dakota, where John Hoeven won the seat being vacated by retiring Democratic Sen. Byron Dorgan.
Democrats saw some good news in Connecticut, where , and in Maryland, where Democratic Sen. Barbara Mikulski won her re-election bid.
Democratic Sens. Patrick Leahy of Vermont and Ron Wyden of Oregon retained their seats, as did Republican Sens. Jim DeMint of South Carolina and Mike Crapo of Idaho.
today showed that voters are disillusioned with Mr. Obama and even more so with Congress.
Voters seem to be willing to put Republicans back in power after growing impatient with the poor economy and high unemployment rates that have lingered under Democratic control.
"Dissatisfaction with the economy and performance of the government is the key to the whole night," said Jeff Greenfield, CBS News Senior Political Correspondent.
President Obama and the Democrats have managed to pass several pieces of legislation in the past two years -- including major packages like health care reform -- but nevertheless face poor approval ratings from voters. For instance, nearly half of voters surveyed nationally in today's preliminary exit polling -- 48 percent -- said health care reform should be repealed.
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Democrats have also struggled to mobilize their core supporters this year the way Republicans have. Today's preliminary exit polling shows that African-American voters -- who President Obama -- represent 10 percent of voters this year, compared with 13 percent in 2008. Hispanics represent 8 percent of voters this year, and 66 percent are voting Democratic. Additionally, just 9 percent of voters are in between the ages of 18 and 29, compared with 18 percent of voters in 2008. Among those young voters, 58 percent are voting Democratic.
Independents make up 28 percent of voters this year, according to the preliminary exit polling, and 56 percent of them are voting Republican. Just 39 percent are voting Democratic. Fifty-five percent of men surveyed are voting Republican, while 43 percent are voting Democratic. Among women, 49 percent are voting Democratic, and 48 percent are voting Republican.
Anxious for results out of Washington, about said in a recent CBS News poll they want Republicans and Mr. Obama to compromise with each other. Voters also want a fresh start: As many as of likely voters in a recent CBS News poll said that most members of Congress should be replaced with someone new.
A new Congress, however, may just mean . A number of conservative candidates like Paul surged to success by refusing to compromise their political principles and winning the support of groups like the Tea Party. In Kentucky, preliminary exit polling shows that 43 percent of voters were Tea Party supporters, including 24 percent who were strong supporters.