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.

With 29 of 35 Senate races called, Democrats were guaranteed at least a 55-45 majority, including two holdover independents who vote with Democrats. But they were hoping for even greater gains in a political environment that clearly favored Democrats.

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.

Democrats now exercise a slim 51-49 control of the chamber. Piggybacking on aggressive Barack Obama voter-registration and get-out-the-vote drives in battleground states, Democrats were reaching for a coveted 60-seat, filibuster-proof Senate majority. However, leaders in both parties portrayed that goal as a long shot.

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.

Senate Republican leader Mitch McConnell, who had been a target of national Democrats, won re-election against two-time Democratic gubernatorial candidate Bruce Lunsford in a contentious race.

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.

Reaching their goal of 60 seats was a stretch. 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.

Democrats’ hoped that only two Democratic senators would lose their Senate seats as a result of the national elections: Biden and Obama. Democratic governors in Illinois and Delaware are sure to appoint Democrats to replace them.

The Senate seats of Obama and GOP presidential candidate John McCain were not up this year.

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 cattle rancher. Johanns resigned as Bush’s agriculture secretary to make the race.

Going into the election, the only Democratic seat that appeared vulnerable was Mary Landrieu’s in Louisiana. Landrieu, however, was leading in early returns against Republican state treasurer John Kennedy.

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.