WASHINGTON — Lawmakers return to Washington on Monday for Congress’s lame-duck session confronting a number of major problems but lacking clear signals from President Trump – even as President-elect Joe Biden and his team are poised to begin engaging with congressional Democrats on their priorities.

Congress faces a government shutdown deadline and crucial economic relief negotiations at a moment of extraordinary national uncertainty, with Trump refusing to concede the presidential election and with coronavirus cases spiking nationwide.

Even before Biden takes office on Jan. 20, Congress must contend with a Dec. 11 government funding deadline. Failure to reach a deal would result in a government shutdown, and Trump has not signaled whether he would sign a new spending bill.

At the same time, House Speaker Nancy Pelosi (D-Calif.) and Senate Majority Leader Mitch McConnell (R-Ky.) have both expressed the desire to pass new economic and health-care relief measures to address the surging coronavirus pandemic – something Congress has not been able to do since the spring. But it is uncertain whether they will be able to find common ground in the weeks ahead: McConnell is pushing for a narrow and targeted bill, while Pelosi continues to insist on a broader and bolder relief package.

Members of Biden’s transition team, meanwhile, are expected to begin conversations with congressional Democrats and aides this coming week to map out a strategy for the lame duck, with the aim of getting money for their priorities in spending legislation before the end of the year, two people familiar with the developments said Sunday. They spoke on condition of anonymity because the conversations were private.

Lame-duck sessions of Congress can be ceremonial affairs, particularly as one presidential administration begins its exit and a new one prepares to take control. But this transition is already shaping up to be much different, with the country facing severe economic uncertainty and the coronavirus pandemic entering a deadly new phase. Since Election Day on Tuesday, Trump has not publicly expressed much interest in changing course on the economy or coronavirus response.

Trump administration officials have indicated they are unlikely to play much of a role in any new round of stimulus talks, instead letting McConnell take the lead. Meanwhile, Biden allies predicted Sunday that Biden and Vice President-elect Kamala Harris will press Congress to produce a compromise coronavirus relief bill that has eluded lawmakers and Trump administration officials for months.

“Joe is going to be able to pull together leaders in Congress to deliver the relief that we need and deserve, and one way that President Trump can show some graciousness in the next 73 days during the transition is to publicly support a significant pandemic relief bill,” Sen. Christopher A. Coons, D-Del., a top Biden surrogate, said Sunday on ABC’s “This Week.”

Biden’s deputy campaign manager, Kate Bedingfield, said that “the work starts right away,” with Biden preparing to announce a coronavirus task force Monday and begin the work of a presidential transition in earnest.

“He’ll be making calls. He’ll be making announcements to the American people about how he’s going to make good on these campaign promises,” Bedingfield said on NBC’s “Meet the Press.”

Despite Biden’s victory, McConnell is likely to retain his role as majority leader in the new Congress, although that outcome depends on the results of two runoff Senate races in Georgia in early January. Pelosi will also continue as speaker, although she will be presiding over a smaller majority after Democrats performed below their expectations in House and Senate races in Tuesday’s election.

Republican lawmakers argued Sunday that those results amounted to a rejection of far-left policies and a call for compromise, most immediately on legislation addressing the coronavirus crisis. Cases are on the rise nationally, and the economy is showing signs of slowing back down after much of the stimulus money Congress approved in the spring has dried up.

“We begin, I think, with an immediate need to get relief to families and small businesses that are suffering as a result of the economic downturn associated with covid,” Sen. Mitt Romney, R-Utah, said on CNN. “That’s something we’re going to have to do, and we’re going to have to do it in a bipartisan way.”

Romney is among just a handful of GOP leaders who have offered congratulations to Biden on his victory. Others, such as Sen. Patrick J. Toomey (R-Pa.), are calling for the vote-counting process to conclude before Biden’s victory can be conclusive, though Toomey said Sunday on CBS that “the media projection is probably correct.”

A handful of Trump’s staunchest allies insisted Sunday that the election is far from over. Sen. Lindsey Graham, R-S.C., who chairs the Senate Judiciary Committee, claimed in an interview on Fox News’s “Sunday Morning Futures” that there have been suspect voting incidents in Pennsylvania, Michigan and elsewhere.

“And I’m hellbent on looking at it,” Graham said. “Do not accept the media’s declaration of Biden. Fight back.”

There is no evidence of any widespread fraud in the election. But the divisions among congressional Republicans over whether to acknowledge Biden as the president-elect mean that negotiations over a new spending package or coronavirus relief bill will proceed under something of a cloud.

Those spending negotiations are expected to begin in earnest this week as lawmakers work to cobble together a massive package wrapping up the 12 annual must-pass spending bills that fund government agencies. McConnell and Pelosi have said they want to finish work on the fiscal 2021 spending bills during the lame-duck session, rather than just passing another short-term funding extension on Dec. 11 that would punt the real work of funding the government to the next administration.

If they cannot agree on new spending legislation, however, a short-term “continuing resolution” would become the likeliest fallback. Any number of thorny issues are likely to arise in the course of spending talks, including how much money to devote to certain programs and language over abortion that perennially divides the parties.

It is uncertain whether the work on spending legislation will collide with negotiations over economic relief measures, which could be attached to the spending bill or move separately. Lawmakers in both parties widely agree on the need for more spending on health-care systems, vaccines, schools and small businesses, and McConnell and Pelosi have indicated support for sending out a new round of $1,200 stimulus checks to individuals.

McConnell also indicated support shortly after the election for sending additional aid to cities and states, something that has been a central Democratic demand. But McConnell and Pelosi have been far apart on the overall price tag of any economic relief legislation, with McConnell arguing this past week that a jobs report showing unemployment had dropped to 6.9 percent supported his push for a narrower relief bill – a position Pelosi rejected.

Pelosi has pushed for legislation with a price tag north of $2 trillion, while McConnell has backed a bill costing around $500 billion. If they cannot get a deal in the lame-duck session, that would leave Biden with the job of cobbling together a new economic relief bill as an early priority when he takes office, while Americans who have been waiting months for additional relief would have to wait even longer.

In another issue pending for the lame-duck session, Congress has yet to unveil or vote on a compromise version of the annual defense authorization bill, which got hung up in a dispute over whether military installations named after Confederate generals should be renamed. Trump had threatened to veto any legislation requiring the name changes.

The Washington Post’s Karoun Demirjian contributed to this report.