WASHINGTON (AP) — Democrats fattened their majority control of the Senate on Tuesday, ousting Republican Sens. Elizabeth Dole of North Carolina and John Sununu of New Hampshire and capturing seats held by retiring GOP senators in Virginia, New Mexico and Colorado.

Piggbacking on the excitement level raised presidential victor Barack Obama and his voter-registration and get-out-the-vote drives, Democrats increased their effective majority to at least 56 seats in the 100-member Senate.

But Republicans stopped a complete rout, holding the Kentucky seat of Senate Minority Leader Mitch McConnell and a Mississippi seat once held by Trent Lott — two top Democratic targets.

North Carolina state Sen. Kay Hagan, little known politically before her run, defeated Dole — a former Cabinet member in two Republican administrations and 2000 presidential hopeful. Dole had tried to tie Hagan, a former Presbyterian Sunday school teacher, to atheists in an ad that appeared to backfire.

In New Hampshire, former Democratic Gov. Jeanne Shaheen defeated Sununu in a rematch of their 2002 contest.

In pair of western races, Reps. Tom and Mark Udall took over Senate seats held by retiring Republicans. Tom Udall, the son of former Interior Secretary Stewart Udall, defeated Republican Rep. Steve Pearce to succeed Pete Domenici in New Mexico. Tom’s cousin Mark, the son of the late Rep. Morris Udall of Arizona, won the Colorado seat held by Republican Wayne Allard, who did not seek re-election.

Democratic former Virginia Gov. Mark Warner breezed to victory to take a Virginia Senate seat long held for by terms by retiring GOP Sen. John Warner. Warner beat another former governor, Republican Jim Gilmore, in the race to replace retiring five-term Sen. John W. Warner. The two Warners are not related.

Democratic vice presidential candidate Joe Biden won another six-year term representing Delaware in the Senate. It became moot when Obama won the presidential election.

Democratic Sen. Mary Landrieu of Louisiana, the only serious GOP target, won her re-election over Republican state treasurer John Kennedy.

Senate Majority Leader Harry Reid, D-Nev., attributed the Democratic gains to Obama’s coattails.

“It’s been a really good night,” Reid said in an interview with The Associated Press. “Obama ran a terrific campaign, he inspired millions of people.”

Senate Republican leader Mitch McConnell, who had been a target of national Democrats after leading successful filibusters against much of their legislative agenda the past two years, won re-election against two-time Democratic gubernatorial candidate Bruce Lunsford in a contentious race.

In a tight Mississippi race, Trent Lott’s temporary replacement, Republican Roger Wicker, defeated former Democratic Gov. Ronnie Musgrove to serve another four years.

With Warner’s victory in Virginia, Democrats now control both Senate seats and the governor’s mansion. Virginia usually votes Republican in presidential elections, but this year Democrats viewed it as one of their most promising pick ups.

Democrats were counting on a slumping economy, an unpopular war and voter fatigue after eight years of President Bush to bolster that majority, building on the six seats they added in 2006.

Democrats had set a sky’s-the-limit goal of controlling 60 Senate seats when the new Congress convenes in January — the magic number needed to prevent Republicans from blocking bills and judicial nominees. It was always a long shot.

But having a majority in the high 50s would enable Democrats to exercise far more control than they have now, since some Republicans probably would join them in efforts to break Senate logjams on many bills and judicial appointments.

They began with the 51-49 majority they’ve held the past two years. That includes two independents, Bernie Sanders of Vermont and Joe Lieberman of Connecticut, who have voted with Democrats the past two years. But Lieberman, the Democrat’s vice presidential nominee in 2000, spent most of 2008 campaigning for McCain.

It was unclear even to Senate leaders Tuesday night whether Lieberman would continue to caucus with the Democrats or keep his chairmanship of the Senate Homeland Security committee. Reid said in the interview that he’ll discuss the matter with the Connecticut senator later this week.

Democrats will lose two incumbents: Obama and Biden. Democratic governors in Illinois and Delaware are sure to appoint Democrats to replace them.

Democrats had fewer seats to defend than Republicans. Of the 35 races on Tuesday’s ballot, 23 are now held by Republicans, 12 by Democrats.

Another possible pickup for Democrats: Sen. Ted Stevens, R-Alaska. Stevens, at 84, the longest serving Republican in Senate history, sought re-election despite calls from GOP leaders to resign after he was convicted last week of seven counts of lying on Senate financial disclosure forms.

He was locked in a tight contest with Democrat Mark Begich, the mayor of Anchorage. Another closely contested race was in Minnesota, where Republican incumbent Coleman was challenged by Democrat Al Franken, the former “Saturday Night Live” writer and actor. A significant third-party candidate, Independent Dean Barkley, was complicating the race.

Republican Sen. Gordon Smith in Oregon was also on the list of Democratic targets.

Republicans held the Nebraska seat of retiring Sen. Chuck Hagel, with former Gov. Mike Johanns defeating Democrat Scott Kleeb, a college history instructor. Johanns resigned as Bush’s agriculture secretary to make the race.

Republicans also held the Idaho seat of Sen. Larry Craig, who decided not to run for re-election after he was caught last year in a men’s room sting. Idaho Lt. Gov. Jim Risch won the seat.

Republican incumbent senators who cruised to re-election included Lindsay Graham in South Carolina, Susan Collins of Maine, Jeff Sessions in Alabama, James Inhofe in Oklahoma, Lamar Alexander in Tennessee, Pat Roberts in Kansas, Thad Cochran of Mississippi, John Cornyn of Texas and Michael Enzi in Wyoming. Sen. John Barrasso, appointed after Wyoming Sen. Craig Thomas died, was elected to fill the remaining four years of Thomas’ term.

Democratic senators easily winning re-election included Jay Rockefeller of West Virginia, Dick Durbin of Illinois, John Kerry of Massachusetts, Frank Lautenberg of New Jersey, Carl Levin of Michigan, Tim Johnson of South Dakota, Mark Pryor of Arkansas, Max Baucus of Montana, Tom Harkin of Iowa and Jack Reed of Rhode Island.