WASHINGTON  Empowered by their election gains, Congressional Republicans are giving little ground to President Obama and weakened Democrats in the final weeks of the 111th Congress, imperiling Democratic efforts to pass major tax and spending legislation, unemployment aid and a nuclear nonproliferation treaty among other issues.

One week into a lame-duck session, Democrats have been unable to gain traction on their top priorities, leaving them casting about for ways to avoid a year-end pileup of expired tax breaks, exhausted jobless benefits and federal agencies running out of money.

Republicans, who will take over the House in January and cut deeply into the Democratic majority in the Senate, appear content to do the minimum possible and push the big fights into the next year, when they will have more power and leverage. The Republicans say Democrats have only themselves to blame because they put off too many matters until after the election.

“While there’s business that needs to be done, I would hope that the leaders that are still in charge would heed the advice of the American people that occurred on Election Day in terms of being prudent in their actions here before the end of the year,” said Representative John A. Boehner of Ohio, the incoming speaker.