WASHINGTON — Democrats broadened their control of Congress in Tuesday’s elections, though in the Senate they fell short of the 60 votes needed for a filibuster-proof majority that would have given them almost unbridled power over legislation.

Voters ousted Senate Republicans in North Carolina and New Hampshire and added three seats held by retiring GOP incumbents to the Democrats’ fragile 51-49 majority. Four other Senate races involving Republican incumbents, including the contest in Minnesota, were too close to call early today. The GOP retained some leverage in spite of Democratic gains.

When Obama and running mate Joe Biden take their oath of office on Jan. 20, Democrats will control both the White House and Congress for the first time since 1994.

“It is not a mandate for a party or ideology but a mandate for change,” said Senate Majority Leader Harry Reid of Nevada.

House Speaker Nancy Pelosi of California said the American people “have called for a new direction. They have called for change in America.” She scheduled a midday news conference on Capitol Hill today to elaborate.

“The people have spoken. We hear the people and now it’s time to come behind our president,” Sen. Kay Bailey Hutchison, R-Texas, told “The Early Show” on CBS today. “The Senate is going to have to work things out in a bipartisan way, and I think the test is going to be right there.”

In the House, Democrats captured GOP-held seats in the Northeast, South and West, adding at least 17 seats to the 30 they took from Republicans in 2006. Fewer than 10 races remained undecided. Going into Tuesday’s election, Democrats controlled the House 235-199 with one vacancy.

The Associated Press called the Senate race in Minnesota prematurely. Republican Sen. Norm Coleman finished ahead of Democrat Al Franken in the final vote count, but Coleman’s 571-vote margin falls within the state’s mandatory recount law. That law requires a recount any time the margin between the top two candidates is less than one-half of 1 percent.

Not one Republican defeated a Senate Democrat.

On the brighter side, the GOP blocked a complete rout in that chamber, holding the Kentucky seat of Senate Minority Leader Mitch McConnell and a Mississippi seat once held by Trent Lott — two top Democratic targets. Also surviving was Sen. Susan Collins, R-Maine, who defeated Democratic Rep. Tom Allen by a nearly 3-2 margin despite Obama’s overwhelming victory in her state.

Exit polls showed that voters were deeply anxious about the economy and dissatisfied with President Bush. They haven’t been thrilled by Democrats in Congress, either, largely because the new majority could not agree on how to end the Iraq war as promised.

Exit polling also showed that the war remains unpopular, and distaste for the conflict helped Obama.

But that issue faded this year. Politically, the economy was the number one issue with voters and nothing else came close, exit polls showed. That hurt McCain and trickled down-ballot, hurting some Republican candidates.

Sen. Elizabeth Dole, R-N.C., the former president of the American Red Cross, a one-time presidential hopeful and a household name in Republican circles, lost her seat after only one term to state Sen. Kay Hagan. It probably wasn’t a surprise.

“You’ve got a situation here where the president’s numbers are absolutely, unbelievably poor,” Dole said in a recent interview. “I also think McCain is underperforming right now.” She predicted that would change.

In New Hampshire, where McCain beat George W. Bush in the 2000 GOP primary, the self-styled maverick lost to Obama. And incumbent Republican Sen. John Sununu lost to former Gov. Jeanne Shaheen.

Other Democrats who won Republican-held seats were former Virginia Gov. Mark Warner, and cousins Mark Udall of Colorado and Tom Udall of New Mexico.

Those wins brought the Democratic Senate majority to 56, but that number was anything but final. Races remained without clear winners early today in Oregon, Alaska and Georgia.

The Democrats’ new majority — for now — includes Connecticut Sen. Joe Lieberman, an independent who has caucused with the party. Many Democrats want to strip him of his chairmanship of the Homeland Security committee, kick him out of the caucus or both because he endorsed his close friend McCain over Obama.

Reid said he was meeting with Lieberman later in the week to discuss the matter. Much rides on how badly Democrats need Lieberman to reach the 60-vote threshold required to block Republican filibusters.

In the House, it was the first time in 75 years that Democrats won major gains in back-to-back elections. They gained 30 seats in the 2006 backlash against several Republican scandals.

This year, their wins changed the political geography, regionally. Ousting 22-year veteran Rep. Chris Shays in Connecticut gave Democrats every House seat from New England.