Mass layoffs of US federal workers are "imminent," the White House warned Thursday, as no compromise was in sight between Democrats and Republicans, who are blaming each other for the budget shutdown that has paralyzed the United States for two days.

"The (White House) Budget Office is working with federal agencies to identify possible cuts, and we believe layoffs are imminent," said White House spokeswoman Karoline Leavitt.

Meanwhile, the Trump administration announced the cancellation of billions of dollars in federal funding promised to Democratic-led states. In New York, it froze $18 billion promised for two public transportation improvement projects.

In total, $26 billion in previously approved federal funds has been frozen. This applies to 16 states, all of which will be won by Democrat Kamala Harris in the November 2024 presidential election.

"The White House's actions appear both unprecedented and punitive, underscoring the risks of an endless budget impasse," the New York Times warned Thursday.

White House Budget Director Russell Vought, for his part, welcomed the budget cuts also affecting green energy projects, such as in California, mocking the "Green New Deal scam."

"Taken hostage"

Some 750,000 civil servants have been on technical unemployment since midnight on Wednesday, penalizing users of public services.

The National Air Traffic Controllers Association (NATCA) said in a statement that it fears for airspace safety due to the temporary layoff of more than 2,300 agents.

Such a "shutdown", unprecedented in seven years, is very unpopular in the United States and - as usual - the two major parties are blaming each other.

"Democrats have shut down government services," the White House said in a message on its website, accompanied by a clock counting down the shutdown.

"They have held the American people hostage in a way that they believe benefits them politically," added Senate Majority Leader John Thune.

The opposition, for its part, laments the lack of good-faith discussions. "Why are (the Republicans) boycotting negotiations? I've never seen anything like this in my life," denounced Democratic Senator Chris Murphy.

According to House Democratic Leader Hakeem Jeffries, the president is displaying "irresponsible and unserious behavior."

In fact, while he has said he wants to avoid paralysis, Donald Trump is also threatening. "A lot of good things can come out of shutdowns, we can get rid of a lot of things we don't want, and those would be Democratic things," he warned Tuesday.

Republicans are proposing in one text a simple extension of the current budget until the end of November, while Democrats are demanding the extension of public health insurance programs for the poorest.

These requests were deemed "ridiculous" by Vice President JD Vance, who made a rare appearance at the White House press conference on Wednesday.

Duration "complicated to predict"

The Republican bill received only 55 votes, including three Democrats. Still too far from the 60 needed for its adoption.

The last shutdown dates back to Trump's first term, from December 2018 to January 2019, a record 35 days. No clear exit option from the crisis appears in sight this weekend.

"It is unclear how long the Democrats will maintain their untenable stance, making the duration of the shutdown difficult to predict," Russell Vought said in a letter to cabinet officials.

The situation will not be resolved until at least Friday, as Congress adjourns Thursday for the Jewish holiday of Yom Kippur.

Faced with the disastrous image that budgetary paralysis sends to Americans, the presidential majority hopes that enough Democratic senators will finally give in.

According to calculations by analysts at the insurance company Nationwide, each week of paralysis could reduce annual US GDP growth by 0.2 percentage points.