Connecticut: Rep. Chris Murphy (D) vs. Linda McMahon (R)
Final result: Rep. Chris Murphy wins
In the closely watched senate race in Connecticut, Democratic Rep. Chris Murphy defeated Republican nominee and professional wrestling executive Linda McMahon, according to a CNN projection.
Murphy will take over the Senate seat being vacated by retiring Sen. Joe Lieberman, an Independent who sided with Democrats.
His win preserves a seat for Democrats who feared losing it to the wealthy McMahon, who spent over $90 million in the last two elections to try to win a Senate seat.
The race was marked by heavy negative advertising.
Indiana: Richard Mourdock (R) vs. Rep. Joe Donnelly (D)
Final result: Rep. Joe Donnelly wins
Democrats scored a major upset in the Indiana Senate race, scooping up a seat in the deeply red state Republicans had expected to hold.
The campaign appeared to turn for the Democrats after the GOP candidate made controversial comments about rape during a televised debate.
Mourdock, the state treasurer, was backed by both tea party supporters and the Republican establishment when he defeated in the primary longtime GOP moderate Sen. Richard Lugar. When that happened, Democrats thought Donnelly, who is conservative and pro-life, had an outside chance of winning the seat.
Mourdock gave Donnelly an opening when during a debate he defended his opposition to abortion even in the case of rape because, "I think even when life begins in that horrible situation of rape, that is something God intended to happen." Top Democrats and Republicans criticized the remark and within days, Donnelly took a substantial lead in one respected Indiana poll.
Maine: Charlie Summers (R) vs. Cynthia Dill (D) vs. former Gov. Angus King (I)
Final result: Former Gov. Angus King wins
Former Gov. Angus King, an Independent, steadfastly has refused to say if he will organize with Democrats or Republicans when he gets to Washington.
King will replace Sen. Olympia Snowe, herself an independent-minded Republican who stunned her colleagues this year when she announced she would retire from the Senate, which she complained has become increasingly partisan.
Democrats are convinced King will side with them. As evidence, they point to King's support for President Barack Obama and many of his policies. In a sign of that confidence, national Democrats ignored the Democratic candidate Dill and spent heavily against Summers in order to help King.
Republicans also believe that King will caucus with Democrats, so they spent millions to defeat him.
But an aide told CNN last week that King still has not made up his mind and won't until he gets to Washington to see the state of play.
Massachusetts: Sen. Scott Brown (R) vs. Elizabeth Warren (D)
Final result: Elizabeth Warren wins
In a key pick-up of a Republican Senate seat, Warren defeated Brown Tuesday, according to a CNN projection.
Warren, a Harvard University law professor and former Obama administration financial consumer advocate, beat the freshman senator who was seeking a full term to the seat he won two years after the death of Democratic senator Ted Kennedy. Brown, the first GOP Senator from deep blue Massachusetts in decades, billed himself as an independent who voted for the needs of Massachusetts, not the demands of either party.
The Warren-Brown race was one of the costliest and nastiest campaigns this cycle. It was marked by Brown's repeated accusations that Warren claimed to be a minority in order to advance her career. She denied that was her motive for listing her ancestry as Native American, saying she was told about her heritage by her family.
Montana: Sen. Jon Tester (D) vs. Rep. Dennis Rehberg (R)