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 war-torn 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 $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.

'No blank check'

Arming and funding Kyiv in its desperate war against the Russian invasion has been a key policy plank for the Biden administration and, while the stopgap is temporary, it does raise questions over the political viability of renewing the multibillion-dollar flow of assistance.

"This is enough to keep the government open, and I'm not going to shut the government down over foreign aid," one House Democrat, Jared Moskowitz, told CNN.

McCarthy said Russia's invasion was "horrendous" but insisted there could be "no blank check" for Ukraine.

"I have a real concern of what's going to happen long term, but I don't want to waste any money," he said.

With tensions running high and Democrats poring over the text of McCarthy's proposal, one of their lawmakers, Jamaal Bowman, triggered a fire alarm in a building housing congressional offices an hour before the House vote.

Bowman's spokesman insisted it was an accident, but Republicans accused him of seeking to delay proceedings.

If Congress had failed to keep the government open, the closures would have begun just after midnight (0400 GMT Sunday) and would likely have bled into the following week, delaying salaries for millions of federal employees and military personnel.

A shutdown would have meant the majority of national parks, for example -- from the iconic Yosemite and Yellowstone in the west to Florida's Everglades swamp -- shutting to the public from Sunday.

The stopgap measure buys legislators time to negotiate full-year spending bills for the rest of fiscal 2024.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)