President Biden’s defense secretary, Lloyd Austin, set himself up for a showdown this week with lawmakers in Congress — both Republicans and Democrats — who are insisting that he lift a Covid vaccine mandate said to be hobbling recruitment and retention efforts and endangering national security.

His timing couldn’t be worse. Congress is poised this week to consider and vote on an $847 billion defense authorization bill that is already two months overdue and needs to pass in the current lame-duck session. Republicans have threatened to go after any number of “woke” military policies with the bill, but they stand the best chance of winning with their no-vax-mandate refrain. 

Speaking to reporters aboard an undisclosed aircraft carrier, Mr. Austin demurred when asked about the political pressure on the Pentagon but sounded adamant about the mandate. “We lost a million people to this virus,” he said, according to the Associated Press. “A million people died in the United States of America. We lost hundreds in DoD. So this mandate has kept people healthy.”

“I’m the guy” who ordered the military to require the vaccine, Mr. Austin added. “I support continuation of vaccinating the troops.”

Last week, nearly 20 Republican governors signed on to a letter to leaders in Congress asking them to rescind the ban and prohibit the administration from reimposing another, either via the Defense Authorization Act up for debate this week or a standalone bill. The mandate is decimating the ranks of National Guards outfits in their states, the governors said.

The U.S. Army, the letter says, is 25 percent short of its recruitment goals, and the Army National Guard is 10 percent below its goals. At least 8,000 active duty troops have been discharged because of the mandate, and Pentagon officials have said the National Guard is planning to cut loose some 14,000 soldiers who have refused the mandate during the next two years.

“As Governors, our ability to respond to natural disasters and conduct emergency operations is contingent upon the strength and size of our National Guard units,” the letter states. “As Congressional leaders, it is your duty to provide for the national defense, and therefore, we call upon you to protect the men and women in uniform — who protect us — from an unnecessary vaccine mandate. As President Biden, himself, stated on September 18, 2022, ‘The pandemic is over.’” 

Some in Congress seem to have gotten the message. The Democratic chairman of the House Armed Services Committee, Representative Adam Smith of Washington, told Politico this weekend that a rollback of the mandate is very much on the table as part of a compromise on the defense authorization, which is expected to be finalized Monday and will be voted on this week.

“I was a very strong supporter of the vaccine mandate when we did it, a very strong supporter of the Covid restrictions put in place by DoD and others,” Mr. Smith said. “But at this point in time, does it make sense to have that policy from August 2021? That is a discussion that I am open to and that we’re having.”

Even if the House doesn’t include language ending the mandate, a group of GOP senators — led by Rand Paul of Kentucky — have said they will block it in that chamber unless an amendment is added doing so. The Republicans want back pay for those already kicked out over the policy, though, something over which the Democrats have balked.

“The Department of Defense COVID-19 vaccine mandate has ruined the livelihoods of men and women who have honorably served our country,” Mr. Paul and the senators wrote in a letter to their colleagues. “While the Department of Defense certainly must make decisions that will bolster military readiness, the effects of the mandate are antithetical to [the] readiness of our force, and the policy must be revoked.”