A liberal veterans group blasted Sen. Tommy Tuberville (R-Ala.) in a new ad for his months-long block on military promotions over the Pentagon’s abortion policy, accusing the senator of “playing political games with our national security.”

“Every day, crises pop up all around the world, crises you may never hear about,” the ad from VoteVets said. “And the world’s greatest military is ever on alert, ready to defend us against any threat, with our best and brightest seated in positions of command. But what if they’re not?”

“For months, one lone senator, Tommy Tuberville, who never served in uniform himself, has held hostage hundreds of military assignments, just to force his social agenda on women in the ranks, freezing all promotions for top military posts, to the chair of the Joint Chiefs of Staff, leaving mission-critical positions to go vacant,” the ad continued.

Tuberville has held up more than 250 military promotions and nominations in the Senate since March in protest of the Pentagon’s policy to offer paid leave and reimburse service members who travel across state lines to obtain an abortion.

After the head of the Marine Corps officially retired lack week, the branch has been left without a confirmed leader for the first time in more than a century.

The White House, current and former Defense officials, and congressional lawmakers have warned the hold is impacting military readiness and jeopardizing national security.

“Our enemies are watching, looking for any vulnerabilities to exploit,” the ad continued. “And Sen. Tommy Tuberville is playing right into their hands, playing political games with our national security.”

“And not one Republican in Congress will stand up to him and let our troops keep us safe,” it said.