The US government barreled towards its first shutdown in six years Tuesday, with funding expiring at midnight after Democrats fought a war of words with Donald Trump and senators rejected a last-ditch bid to keep the lights on.

Despite frenetic negotiations in Congress, there has been no breakthrough between Democrats and Republicans to fund the government beyond Tuesday -- which marks the end of the fiscal year.

With just hours to spare, Senate Republicans tried to rubber-stamp a House-passed temporary funding patch -- but could not get the handful of Democratic votes required to send it to Trump's desk.

"We'll probably have a shutdown," the Republican president had told reporters in the Oval Office before the vote, seeing the writing on the wall. 

Trump's assessment came after a last-gasp meeting at the White House on Monday yielded no deal, with top Senate Democrat Chuck Schumer saying afterward that "large differences" remained between the sides.

Beyond the lack of progress, the negotiations have been unusually bitter, with House Democratic Minority Leader Hakeem Jeffries berating Trump over a "racist and fake" AI-generated video the president posted after the meeting.

"Mr President, the next time you have something to say about me, don't cop out through a racist and fake AI video," Jeffries told a news conference. 

"When I'm back in the Oval Office, say it to my face." 

The clip mocked Schumer and Jeffries in vulgar terms, falsely depicting them announcing plans to entice illegal immigrants with benefits, while showing Jeffries wearing a sombrero and bushy mustache as mariachi music plays.

Trump in turn blamed Democrats over the stalled talks and threatened to punish the party and its voters during any stoppage by targeting progressive priorities and forcing mass public sector job cuts.

Mass layoffs

"So we'd be laying off a lot of people that are going to be very affected. And they're Democrats, they're going to be Democrats," Trump added at a later White House event.

He said a "lot of good can come down from shutdowns," and suggested he would use the pause to "get rid of a lot of things we didn't want, and they'd be Democrat things."

The move would add to the pain of government workers after large-scale firings orchestrated by tycoon Elon Musk's Department of Government Efficiency earlier this year.

Democrats, in the minority in both chambers of Congress, have been seeking to flex rare leverage over the federal government, eight months into Trump's barnstorming second presidency that has seen entire government agencies dismantled.

The 100-member Senate requires 60 votes to pass government funding bills -- seven more than the Republicans control.

A shutdown would see nonessential operations grind to a halt, leaving hundreds of thousands of civil servants temporarily without pay, and payment of many social safety net benefits potentially disrupted.

US government shutdowns are deeply unpopular, and Democrats and Republicans alike try to avoid the scenario -- while blaming the other camp in the event of a closure.

House Republicans have passed a stopgap measure to extend funding until late November, pending negotiations on a longer-term spending plan.

But Democrats want to see hundreds of billions of dollars in healthcare spending for low-income households restored, which the Trump administration is likely to eliminate.

The gridlocked Congress regularly runs into deadlines to agree on spending plans, and while the negotiations are typically fraught, they do not result in shutdowns.

The longest shutdown in history -- and the latest -- came during Trump's first term, when government functions were halted for 35 days beginning December 2018.