A group of Republican senators is increasingly ready to shut down the federal government in order to stop President Joe Biden's vaccine mandates. On Wednesday, the House failed to vote as planned on a short-term budget resolution to keep the government open past Friday, when the current spending authorization expires.

Holding things up is a demand from some Republicans that the next budget agreement not contain funds for enforcing the various vaccine mandates issued by the Biden administration, including one that requires members of the military to get the jab, and another that would require employers with 100 or more workers to get vaccinated or take periodic COVID-19 tests.

The House Freedom Caucus sent a letter to Senate Minority Leader Mitch McConnell (R–Ky.) that asks him to use "all procedural tools" at his disposal to pass a continuing resolution that prohibits funding for "unAmerican" and "unlawful" vaccine mandates.

It's a sentiment that's being echoed in the Senate as well.

Sen. Mike Lee (R–Utah) is reportedly leading the effort, and urged his fellow GOP senators to support a shutdown at a lunch on Wednesday, reports Politico.

"I think we should use the leverage we have to fight against what are illegal, unconstitutional and abusive mandates from a president and an administration that knows they are violating the law," Sen. Ted Cruz (R–Texas) told reporters on Wednesday, reports The Washington Post.

Cruz, you'll recall, led a successful effort in 2013 to hold up another spending bill because it contained funding for Obamacare. That resulted in a 16-day shutdown of the federal government.

Many Republican senators were critical of Cruz's maneuvering at the time, arguing—correctly, as it turns out—that the GOP would be blamed for a government shutdown that had no hope of actually ending Obamacare.

The backlash from that episode perhaps explains why a number of anti–vaccine mandate Republicans are nevertheless trying to throw cold water on their colleagues' demand for a shutdown over funding said mandates.

"Shutdowns almost never work out," said Sen. Roy Blunt (R–Mo.) to Politico.

McConnell has been pretty tight-lipped about the whole affair. He reportedly said nothing at the lunch where Lee urged senators to back a continuing resolution with no funding for vaccine mandates, opting instead to silently eat two pieces of chicken.

He told reporters on Tuesday that there would be no shutdown, reports the Post.

Senate Majority Leader Chuck Schumer (D–N.Y.), for his part, has said that the two parties are making progress in their budget talks, and cautioned GOP senators against causing what he branded as a "needless Republican government shutdown."

Unfolding in the background of these budgetary machinations are a host of legal challenges to the White House's vaccine mandates.

In late November, the Biden administration asked an appeals court to lift a stay on its vaccine mandate for private employers. That stay had been issued by the U.S. Court of Appeals for the 5th Circuit earlier that month. Several members of the military, represented by former Trump lawyer Sidney Powell, have also sued over a requirement that service members get the jab or face dishonorable discharge.