WASHINGTON — Democrats won a narrow majority in the Senate on Tuesday, snatching Republican-held seats in Massachusetts and Indiana and turning back fierce, expensive challenges in Virginia, Ohio and Connecticut to maintain the control they've held since 2007.

With a third of the Senate up for election, Republicans were undone by candidate stumbles, with GOP hopefuls in Missouri and Indiana uttering clumsy statements about rape and abortion that did severe damage to their chances and the party's hopes of taking over. The losses of Senate seats in Massachusetts and Indiana, combined with independent Angus King's victory in the Republican-held Maine seat, put the GOP too far down in their already uphill climb.

Democrats held open seats in Virginia and were leading in New Mexico, North Dakota and Wisconsin shortly before midnight. Republicans took the Nebraska seat as GOP candidate Deb Fischer denied former Sen. Bob Kerrey's bid to return to the Capitol.

Senate Majority Leader Harry Reid, D-Nev., spoke of conciliation.

"Now that the election is over, it's time to put politics aside and work together to find solutions," Reid said in a statement. "The strategy of obstruction, gridlock and delay was soundly rejected by the American people. Now they are looking to us for solutions."

Democratic Rep. Joe Donnelly edged out tea party-backed Indiana state treasurer Richard Mourdock in a race rocked by the Republican candidate's awkward remark that pregnancy resulting from rape is "something God intended."

Mourdock also upset some Indiana voters for his decision to sue to stop the federal auto bailout of Chrysler, which means jobs building transmissions to thousands in Kokomo. And he alienated some in his own party with his divisive win over six-term Sen. Richard Lugar in the May GOP primary. Lugar refused to campaign for him.

In Massachusetts, Democrat Elizabeth Warren knocked out Republican Sen. Scott Brown, who had stunned the political world in January 2010 when he won the late Sen. Edward M. Kennedy's seat. The strong Democratic tilt in the state and President Barack Obama's easy win over former Gov. Mitt Romney in Massachusetts helped the consumer advocate in her bid.

The race was one of the most expensive in the country — $68 million — even though both candidates agreed to bar outside spending.

In Missouri, Democratic Sen. Claire McCaskill was considered the most vulnerable incumbent, but Republican Rep. Todd Akin severely damaged his candidacy in August when he said women's bodies have ways of avoiding pregnancy in instances of "legitimate rape." GOP leaders, including Romney, called on him to abandon the race. Akin stayed in.

In Virginia, Democrat Tim Kaine edged out Republican George Allen in a battle of former governors. The contest attracted millions of dollars in outside spending.

Democrats currently hold a 53-47 edge in the Senate, including the two independents who caucus with them. Republicans needed a net gain of four seats to grab the majority. Shortly, after 11 p.m., Democrats gained a lock on 50 seats, enough to keep control once President Barack Obama won re-election.

The caustic campaign for control of the Senate in a divided Congress was marked by endless negative ads and more than $1 billion in spending by outside groups on races from Virginia to Montana, Florida to New Mexico. The outcome in Ohio and Virginia was closely linked to the presidential race. Republicans and Democrats in Massachusetts, North Dakota and Montana hoped that energetic campaigns and personality would lead to ticket-splitting by voters

In Maine, independent Angus King prevailed over Republican Charlie Summers and Democrat Cynthia Dill in the race to replace Republican Sen. Olympia Snowe, who blamed partisan gridlock in Washington for her unexpected decision to retire after 18 years in the Senate. Senate Majority Leader Harry Reid, D-Nev., wasted no time, reaching out to King, according to a Senate aide.

In Ohio, Democratic Sen. Sherrod Brown survived an onslaught of outside spending, some $30 million, to defeat state treasurer Josh Mandel. In Pennsylvania, Democratic Sen. Bob Casey survived a late scare from businessman Tom Smith, who invested more than $17 million of his own money in the race.

Democratic Rep. Chris Murphy won the Connecticut Senate seat held by Sen. Joe Lieberman, the independent who was the Democratic Party's vice presidential nominee in 2000. Murphy's win marked the second straight defeat for former wrestling executive Linda McMahon, who spent $50 million of her own wealth in a failed effort against Sen. Richard Blumenthal in 2010 and more than $42 million this election cycle.

Texas sent tea party-backed Ted Cruz to the Senate as the Republican won the seat held by retiring GOP Sen. Kay Bailey Hutchison. Cruz will become the third Hispanic in the Senate, joining Sen. Bob Menendez, D-N.J., and Marco Rubio, R-Fla.

In Florida, Democratic Sen. Bill Nelson triumphed in his bid for a third term, holding off a challenge from Republican Rep. Connie Mack. Republican groups had spent heavily against Nelson early in the race, but the moderate Democrat was a prolific fundraiser with wide appeal among Democrats and some Republicans in the Panhandle.

Independent Sen. Bernie Sanders won a second term in Vermont. Democratic Sens. Sheldon Whitehouse in Rhode Island, Ben Cardin in Maryland and Tom Carper in Delaware were all re-elected. Cruising to another term were Democratic Sens. Debbie Stabenow in Michigan, Kirsten Gillibrand in New York, Amy Klobuchar in Minnesota and Menendez in New Jersey..

In West Virginia, Democratic Sen. Joe Manchin won a full term even though his state went heavily for Republican presidential nominee Mitt Romney.

Tennesseans gave Republican Sen. Bob Corker a second term. Wyoming voters did the same for Sen. John Barrasso, and Republican Roger Wicker captured another term in Mississippi.

King has resolutely refused to say which party he'd side with if elected. But members of both parties have indicated that they expect the former Democratic governor and Obama supporter to align with Democrats. One factor could be the million-plus dollars that Republican-leaning groups such as the U.S. Chamber of Commerce and Karl Rove's organization spent on ads criticizing King.

The arithmetic was daunting for Democrats at the start of the election cycle — they had to defend 23 seats to the GOP's 10. Further complicating the calculation were Democratic retirements in Virginia, Wisconsin, North Dakota, Hawaii, Nebraska and New Mexico as well as the retirement of Lieberman.

Republicans had to deal with retirements in Arizona and Texas in addition to Maine.

Democrats and Republicans in a dozen states faced an onslaught of outside money that financed endless negative commercials and ugly mailings that left voters exasperated. The record independent spending — $50 million in Virginia and $40 million in Wisconsin in addition to $33 million in Ohio — reflected the high-stakes fight for the Senate.