As a new era of divided government looms in the US, Democrats are rushing to complete a lengthy legislative to-do list that includes landmark civil liberties legislation, a routine but critical spending package and a bill to prevent another January 6.

There are only a handful of working days left before the balance of power in Congress shifts and Democrats’ unified control of government in Washington ends. In January, Republicans will claim the gavel in the House, giving them veto power over much of Joe Biden’s agenda.

Meanwhile, Democrats will retain – and possibly expand, depending on the outcome of a runoff election in Georgia – their majority in the Senate, allowing them to continue confirming Biden’s judicial and administrative nominees.

With a narrowing window to act, Democrats intend to use the end-of-year “lame duck” session to leave a legislative mark while they still control all the levers of power in Washington. But they are also under mounting pressure to act to raise the statutory debt limit, staving off a partisan showdown next year that many fear could lead to economic calamity.

“We are going to try to have as productive a lame-duck session as possible,” the Senate majority leader, Chuck Schumer, said at a post-election press conference. “It’s going to be heavy work, long hours to try and get much done.”

Among the unfinished business is enacting legislation to keep the federal government funded past a 16 December deadline. Failure to do so would result in a government shutdown. Lawmakers must also reauthorize the annual National Defense Authorization Act (NDAA), a must-pass bill that sets US military policy for the coming year.

Democrats must also decide whether to confront the debt limit. House Republicans have threatened to use the debt ceiling as leverage to extract deep spending cuts, a prospect that has raised alarm among economists and policymakers who are pleading with Democrats to defuse a dangerous fiscal standoff.

In an interview with CNN, Congressman Hakeem Jeffries, who is poised to succeed Nancy Pelosi when she steps down as the House Democratic leader in January, said raising the debt ceiling before Republicans take control of the House was probably “the right thing to do” as a way to prevent conservatives “from being able to hold the American economy hostage”.

The debt ceiling now stands at $31.4tn, a level that will need to be addressed by the third quarter of 2023, according to projections.

Yet Democratic leaders have suggested that it is unlikely Congress will address the borrowing limit in the next few weeks.

Schumer said last week that he would like to “get a debt ceiling done in this work period” but insisted that it would require Republican support, effectively ruling out a go-it-alone approach that would allow Democrats to unilaterally raise the debt limit. Speaking to reporters on the same day, the Senate Republican leader, Mitch McConnell, said he didn’t think Congress would take up the issue until “sometime next year”.

In a Washington Post op-ed, Peter Orszag, the former director of the Office of Management and Budget and the Congressional Budget Office, implored Democrats to prioritize the issue, even if it takes up precious floor time to accomplish.

“Any Democrats averse to taking such a painful vote now should consider how much leverage their party will lose once Republicans control the House – and how much higher the risk of default will be then,” he wrote. “It’s generally not a good idea to enter a negotiation with a ticking timebomb and a counter-party willing to let it go off.”

While fiscal matters are at the center of negotiations on Capitol Hill, there are many more legislative items on the agenda.

Schumer said the Senate will take a final vote on legislation to protect same-sex and interracial marriages when the chamber returns after the Thanksgiving recess. Earlier this month, 12 Republicans joined all Democrats to clear a major procedural hurdle that put the historic measure on track to passage.

“Passing the Respect for Marriage Act is no longer a matter of if but only of when,” he said in recent remarks. A version of the bill passed the House earlier this year, with support from dozens of Republicans.

Meanwhile, the Senate also hopes to enact reforms to a 19th-century elections law that Donald Trump attempted to exploit to reverse his defeat in 2020, which led to the insurrection at the Capitol.

A bipartisan proposal would overhaul the Electoral Count Act, clarifying that the role of the vice-president, who presides over the certification of the electoral votes as president of the Senate, is purely ceremonial. That means the vice-president could not unilaterally throw out electoral votes, as Trump and his allies pressured his vice-president, Mike Pence, to do. If the bill passes, it would be the most substantive legislative response to the events of January 6.

The White House is also eager for Congress to approve additional financial support for Ukraine, as the nation defends itself against a Russian invasion. The House Republican leader, Kevin McCarthy, who could be the next speaker if he can survive a revolt among hardline conservatives in his caucus, signaled that Republicans would use their majority to limit – or possibly oppose – future spending on the war.

Previous aid packages to Ukraine have been approved with overwhelming bipartisan support, and the president and Democratic leaders are hopeful that a new package can be achieved. Fears that Republicans could cut off aid just as Ukraine forces Russia into retreat with the assistance of US weaponry may motivate lawmakers to authorize vast new spending for Ukraine. The White House has also asked for additional funding to prepare for a possible winter surge of coronavirus infections, though Republicans are unlikely to back the request.

Constrained by the calendar and their narrow majorities, a host of other Democratic priorities will probably remain out of reach as the sun sets on their power in Washington.

A group of Democrats is urging Congress to pass immigration reform and ensure legal protections for Dreamers, undocumented immigrants brought to the US as children, while efforts are under way to reach an agreement on cannabis-related legislation. Senator Raphael Warnock, whose Georgia runoff election will determine the margin of Democrats’ control next year, has continued his push to cap the cost of insulin.