The US Congress passed an 11th-hour funding bill Saturday to keep federal agencies running for another 45 days and avert a costly government shutdown -- although the deal left out aid to Ukraine requested by President Joe Biden.

Three hours before the midnight Saturday deadline, the Senate voted to keep the lights on through mid-November with a resolution that had advanced earlier from the House of Representatives in a day of high-stakes brinkmanship on Capitol Hill.

The last-ditch "continuing resolution" was pitched by House Speaker Kevin McCarthy as millions of public workers looked set to be sent home unpaid, upending government functions from military operations to food aid to federal policymaking.

Biden is set to sign the measure into law in the coming hours, with a White House official telling AFP the administration expects Republicans to allow a quick separate vote on Ukraine aid.

The shutdown crisis was largely triggered by a small group of hardline Republicans who had defied their own party leadership to scupper various temporary funding proposals as they pressed for deep spending cuts.

Saturday's bill kept federal spending at current levels and House Democratic leader Hakeem Jeffries called the lower chamber's vote "a complete and total surrender by right-wing extremists."

But the result could end up costing McCarthy his job. The 21 hardliners had threatened to remove him as speaker if a stopgap measure they opposed was passed with Democrat support.

One of the group, Lauren Boebert, declined to say after the House vote whether she and her colleagues would try to force McCarthy out, but she was clearly unhappy with the outcome.

"There are too many members here who are comfortable doing things the way they've been done since the mid '90s," she told reporters. "And that's why we're sitting at USD 33 trillion in debt."

McCarthy sought to convey confidence both about his own future and the prospects for securing a final agreement within the new timeframe.

"In 45 days we should get our work all done," he said while seeming to offer a hand to the hardliners, saying, "I welcome those 21 back in."

While the crisis highlighted Republican divisions, Jeffries held his caucus together, with only one member defecting in a protest of the lack of assistance to Ukraine.