WASHINGTON — House and Senate leaders marked the first day of the 111th Congress by preaching bipartisanship Tuesday and promising to start work quickly on President-elect Barack Obama's economic proposals and issues ranging from climate change to health care.

Oaths of office were administered, anti-war protesters staged demonstrations and lobbyists cruised through a series of receptions to celebrate the day. More than a few new members said they were eager to get started.

"The overwhelming feeling is, let's get something done," said Colorado Democrat Sen. Mark Udall, who was sworn in on a Bible he said belonged to his father, Morris, who was a congressman for 30 years.

Though Congress often delays substantive action until after the presidential inauguration — which takes place Jan. 20 this year — the economic crisis has prompted urgency. Obama met with leaders of both parties Monday to discuss a $775 billion recovery plan.

"This is the lesson and legacy of the last election: The American people demanded a new era of change and accountability," said House Speaker Nancy Pelosi, D-Calif., who was elected to a second term as speaker. "We need action and we need action now."

The economy is not the only item up for discussion. Congress may also move quickly on an expansion of a children's health insurance program and a bill that requires employers to pay equal compensation for women and men who perform similar work.

Senate committees, meanwhile, have started to schedule confirmation hearings on Obama's Cabinet nominees. That process will begin Thursday with Tom Daschle, Obama's choice for Health and Human Services secretary.

Democrats gained 21 seats in the House in the November election and could pick up as many as eight votes in the Senate, depending on the outcome of disputes in Minnesota and Illinois. In all, there are 63 new members of the House and Senate.

Vice President-elect Joe Biden was sworn into a seventh Senate term Tuesday, although he will vacate his Delaware seat later this month for his new job. Dozens waited to take pictures with Biden at a reception after his swearing in.

Mike Migliore, a former Biden aide who is now a corporate lawyer in Wilmington, was among those who made the trek from Delaware to see Biden. No matter his title, people "still will see him as their senator," Migliore said. "They love him."

Lobbyists also turned out for invitation-only parties to mark the new Congress. "It's good to be in the mix," said Emily Wilson, a lobbyist for the American Society for Radiation Oncology.