WASHINGTON — The new Congress opened for business at the stroke of noon on Tuesday, eager to join President-elect Barack Obama in tackling the worst economic crisis in generations. Democrats celebrated last fall's election gains in the House and Senate.

Vice President Dick Cheney called the Senate to order at midday, then began the ceremonial duties of swearing in 32 senators who triumphed in November elections.

Democrat Roland Burris of Illinois was not among them — informed he would not be seated because his paperwork was not in order. He pledged a lawsuit, the latest twist in a political drama that began when he was appointed by Gov. Rod Blagojevich, charged with having attempted to sell the seat.

Across the Capitol, Lorraine C. Miller, clerk of the House, rapped the opening gavel, prelude to a day of ceremony highlighted by Nancy Pelosi's re-election as speaker. "We need action and we need action now," she said minutes after taking the gavel, symbol of her authority.

Democrats looked ahead to two years of increased strength after picking up seats in both houses — at least seven in the Senate and 21 in the House. With their gains — as well as with Obama in the White House after Jan. 20 — they looked forward to an agenda of fixing the economy, ending the war in Iraq, expanding health care and more.

Senate Majority Leader Harry Reid celebrated the approaching end of the Bush administration in remarks on the Senate floor that also called for bipartisan cooperation.

"We are ready to answer the call of the American people by putting the past eight years behind us and delivering the change that our country desperately needs," he said.

And yet, he told Republicans, "we are in this together," when it comes to the wars in Iraq and Afghanistan, the economic crisis and more.

The day was heavy on ceremony.

The Senate galleries were crowded as Cheney administered the oath to senators in groups of four. Sen. Joseph Biden of Delaware was among them, taking the oath of office for a seat that he has held for more than three decades, and will relinquish in a matter of days to become Obama's vice president.

The atmosphere in the House was family-friendly as children, grandchildren and other relatives joined lawmakers in the large chamber, lit for television.

Sean and Tommy Rooney, ages 5 and 7, wore T-shirts with their last name on the back. Their father, Rep. Thomas Rooney, is a freshman Republican from Florida.