Republicans retained control of the U.S. House of Representatives while Democrats held onto the U.S. Senate in Tuesday's national election. In Massachusetts, Democrat Elizabeth Warren unseated Sen. Scott Brown, R-Mass., while Virginia Gov. Tim Kaine defeated Republican George Allen to hold onto a Democratic Senate seat.
Below is a breakdown of several key contested Senate races.
Connecticut Senate
Rep. Chris Murphy, D-Conn., defeated Republican Linda McMahon with 53 percent of the vote as of press time, filling an open Senate seat in Connecticut. The seat was previously held by Independent Joe Lieberman.
McMahon, former chief of World Wrestling Entertainment, spent more than $40 million of her personal fortune to finance the race. In 2010, she unsuccessfully ran for the Senate seat now occupied by Sen. Richard Blumenthal, D-Conn. In that race, McMahon spent $50 million of her own money.
Murphy has traditionally voted along Democratic party lines while in Congress. He was endorsed by President Obama and narrowly led in polls heading into Tuesday's contest.
Obama won the state's seven electoral college votes.
Indiana Senate
Rep. Joe Donnelly, D-Ind., won the state's open Senate seat, defeating Republican State Treasurer Richard Mourdock and adding a Democratic Congressional seat. Donnelly received 49 percent of the vote as of press time.
Mourdock, a Tea Party favorite, defeated incumbent Sen. Richard Lugar, R-Ind., in the state's primary earlier this year. Despite the state's conservative leanings, Mourdock polled behind Donnelly in the race's final days, a change attributed in part to statements he made about abortion and rape in an Oct. 23 debate.
Mourdock, who said pregnancy caused by rape is "something that God intended to happen," drew criticism from Republican candidates, including Mitt Romney, who had previously endorsed him.
Romney won Indiana's 11 electoral college votes.
Maine Senate
Former Maine Gov. Angus King, an Independent, defeated Republican Charlie Summers and Democrat Cynthia Dill in the race to replace Sen. Olympia Snowe, R-Maine.
King led the polls heading into Tuesday's electoral contest and received 55 percent of the vote as of press time.
Snowe, a moderate Republican, announced her intentions to step down last spring, citing growing partisanship in Congress.
A former Democrat, King has not explicitly committed to voting with either major party, though Democrats widely expect him to caucus with them.
Massachusetts Senate
In this year's most expensive Senate race, Harvard law professor Elizabeth Warren defeated Sen. Scott Brown, R-Mass., for the seat formerly occupied by Democrat Ted Kennedy. As of press time, Warren received 53 percent of the vote.
The race, in which more than $70 million was spent, is also the most expensive in Massachusetts' history and was expected to draw a record turnout.
Scott Brown, who trailed in polls leading up to the election, won the traditionally liberal seat in a special election following Kennedy's death in 2010. Warren shot to national prominence after helping create the Consumer Financial Protection Bureau in 2011.
Obama reportedly considered Warren to head the bureau but did not believe she would be approved by Republican legislators.
Obama won the state's 11 electoral college votes.
Missouri Senate
Sen. Claire McCaskill, D-Mo., defeated Republican challenger Rep. Todd Akin, R-Mo., in a race that attracted national attention after statements Akin made about abortion rights.
As of press time, McCaskill received about 52 percent of the vote compared to about 42 percent for Akin.
Akin held a substantial lead over McCaskill in early polls. But this summer, after Akin commented on abortion and the status of "legitimate rape," the race's dynamics shifted with McCaskill polling ahead for the remainder of the contest. Following those comments, Akin was repeatedly called upon by his own party to remove himself from the contest.
Missouri remains strongly conservative, with Romney winning the state's 10 electoral college votes.
Montana Senate
Sen. John Tester, D-Mont., led against Rep. Denny Rehberg, R-Mont., but the race was too close to call as of press time.
Heading into the race, Rehberg held a slight lead over Tester, whose 2006 victory was an anomaly in a typically conservative state.
Tester distanced himself from Obama throughout the campaign, positioning himself as an independent Democrat.
Mitt Romney won Montana, which has 3 electoral college votes.
Nevada Senate
Incumbent Sen. Dean Heller, R-Nev., defeated challenger Rep. Shelley Berkley, D-Nev., 46 percent to 45 percent, CNN projected early this morning.
Heller, who polled ahead of Berkley heading into the race, was called on to fill the seat earlier this year, after former Sen. John Ensign, R-Nev., was forced to resign.
The contest attracted national attention after the New York Times reported that Berkley had led an effort to maintain funding for a kidney transplant program that also benefited her husband's medical practice. Following the story, the House's Committee on Ethics launched an official inquiry into the matter.
Obama won the swing sta
te, receiving six electoral votes.
Wisconsin Senate
Rep. Tammy Baldwin, D-Wis., will be the nation's first openly gay senator and Wisconsin's first female senator after defeating former Republican governor Tommy Thompson, receiving 51 percent of the vote as of press time.
Wisconsin had been heavily contested by both parties following a failed attempt to recall Republican Gov. Scott Walker.
The seat had been held by a Democrat since 1957, most recently by Herb Kohl, who will retire after four terms. Entering the election, Baldwin held a slight lead in the polls over Thompson, who attracted criticism for statements he made about cutting Medicare and Medicaid.
Baldwin was endorsed by former President Bill Clinton, while former President George H.W. Bush endorsed Thompson.
In the presidential contest, Obama won Wisconsin, which carries 10 electoral votes.
Virginia Senate
Former Democratic Gov. Tim Kaine defeated Republican George Allen to fill a vacant Virginia Senate seat. As of press time, Kaine had received about 52 percent of the vote.
The candidates, who remained neck-and-neck until election day, vied to fill a spot being vacated by Sen. Jim Webb, D-Va.
Kaine, who previously headed the Democratic National Committee, ran as a moderate Democrat.
Allen previously ran for the seat in 2006, but he lost to Webb after calling an Indian American Democratic worker a "macaca." The incident was seen as derailing both Allen's Senate bid and any White House ambitions he might have had.
Virginia, a swing state in the presidential election, cast 13 electoral votes for Romney.
