US lawmakers returned to Washington on November 29 staring down a critical holiday season to-do list that juggles President Joe Biden’s domestic spending priorities with keeping the government open and averting a catastrophic debt default.

Senators are bracing for what is shaping up to be the one of the most gruelling Decembers in years, with defence funding and the expanding probe into the January 6 insurrection on Capitol Hill likely to add to the workload.

But the top priority is government funding, with federal agencies due to run out of cash on November 26.

A lasting deal to avoid a damaging shutdown would require agreement on spending bills for the 2022 fiscal year, as the government is still funded at levels approved during Donald Trump’s administration.

With no consensus in sight, House leaders are expected to introduce a stop-gap funding bill through January, with a vote as early as December 1, to avoid thousands of public employees being sent home without pay.

“We begin an important week for what will be an important final month of 2021 . . . With so many critical issues, the last thing the American people need right now is a government shutdown,” the Senate’s Democratic leader Chuck Schumer said on the floor.

Next up, treasury secretary Janet Yellen says the government must raise the debt ceiling by December 15 to avoid a credit default that would leave the country unable to repay debts or secure new loans.

With Wall Street and world markets watching closely, Schumer and his minority Republican counterpart Mitch McConnell remain at odds over how to handle the extension.

McConnell says the Democrats need to boost the debt limit on their own as they assemble a $1.8-trillion package of new social spending and climate programmes.

The Kentucky state Republican insisted when the fight came up in October that his senators would not help but was criticised by his own side for caving and lining up 11 Republicans to pass a temporary extension.

The Democrats point out that Republicans helped run up debts and so should help raise the ceiling in the normal way, with backing from both parties.

“You know, if the Republicans want to scrooge out on us, and increase people’s interest rates and make it hard to make car payments – go ahead, make that case,” Democratic Senator Amy Klobuchar told ABC on November 28.

“We’re going to stop them from doing that.”

The Senate is also due to take up the National Defence Authorisation Act, a massive bill that Congress has reliably passed for six decades.

Democrats are hoping to wave it through this week, but Republicans could scupper that timeline by demanding votes on an array of amendments from Afghanistan policy and repealing Iraq War authorisations to women registering for the military draft and the US-China relationship.

Biden heads into the New Year with support waning among independent voters – a key group that helped catapult him to the White House – over the gridlock on Capitol Hill, spiralling inflation and the stubborn pandemic.

Progressive and moderate Democrats are still fighting over crucial, high-dollar parts of Biden’s Build Back Better package, which Schumer is hoping to send back to the House for a rubber stamp before Christmas Day.