Senate Majority Leader Mitch McConnell has shut the door on President Donald Trump's push for $US2000 ($A2600) COVID-19 relief cheques, declaring Congress has provided enough pandemic aid as he blocked another attempt by Democrats to force a vote.
The GOP leader made clear he is unwilling to budge, despite political pressure from Trump and even some fellow Republican senators who demanded a vote.
Trump wants the recently approved $US600 ($A800) in aid increased threefold. But McConnell dismissed the idea of bigger "survival checks", saying the money would go to plenty of American households that don't need it.
McConnell's refusal to act means the additional relief Trump wanted is all but dead.
"We just approved almost a trillion dollars in aid a few days ago," McConnell said, referring to the year-end package Trump signed into law.
McConnell added, "if specific, struggling households still need more help," the Senate will consider "smart targeted aid. Not another fire hose of borrowed money".
The showdown between the outgoing president and his own Republican Party over the cheques has thrown Congress into a chaotic year-end session just days before new lawmakers are set to be sworn into office.
It's one last stand-off, together with the override of Trump's veto of a sweeping defence bill, that will punctuate the president's final days and deepen the GOP's divide between its new wing of Trump-styled populists and what had been mainstay conservative views against government spending.
Trump has been berating the GOP leaders, and tweeted, "$2000 ASAP!"
For a second day in a row, Senate Democratic leader Chuck Schumer tried to force a vote on the bill approved by the House meeting Trump's demand for the $US2000 ($A2600) checks.
"What we're seeing right now is Leader McConnell trying to kill the checks - the $2,000 checks desperately needed by so many American families," Schumer said at the Capitol.
The roadblock set by Senate Republicans appears insurmountable. Most GOP senators seemed to accept the inaction even as a growing number of Republicans, including two senators in runoff elections on January 5 in Georgia, agree with Trump's demand, some wary of bucking him.
Congress had settled on smaller $US600 ($A800) payments in a compromise over the big, year-end relief bill Trump reluctantly signed into law. Treasury Secretary Steven Mnuchin said those checks will begin to go out Wednesday.
With the Georgia Senate runoff elections days away, leading Republicans warned that the GOP's refusal to provide more aid as the virus worsens could jeopardise the outcome.
"The Senate Republicans risk throwing away two seats and control of the Senate," said Newt Gingrich, the former congressional leader, on Fox News. He called on Senate Republicans to "get a grip and not try to play cute parliamentary games with the president's $2,000 payment".
House Speaker Nancy Pelosi said, "These Republicans in the Senate seem to have an endless tolerance for other people's sadness."
McConnell had earlier unveiled a new bill loaded up with Trump's other priorities as a possible off-ramp for the stand off.
It included the $US2000 ($A2600) cheques as well as a complicated repeal of protections for tech companies like Facebook or Twitter under Section 230 of a communications law that the president complained are unfair to conservatives.
It also tacked on the establishment of a bipartisan commission to review the 2020 presidential election Trump lost to President-elect Joe Biden.
Democrats opposed that approach and it does not have enough support to pass the Senate. No votes on additional aid are scheduled.