Republican Sen. Markwayne Mullin of Oklahoma has placed a hold on the promotion of Lt. Gen. Christopher Donahue, preventing his elevation to lead U.S. Army forces in Europe.

Donahue, currently a three-star general, was nominated earlier this month by President Joe Biden to become a four-star general. He was a key military official involved in overseeing the chaotic withdrawal of U.S. forces from Afghanistan, The Daily Wire reported.

At the time of the withdrawal, Mullin, then serving in the House of Representatives, attempted to spearhead his own efforts to evacuate Americans from Afghanistan but was repeatedly obstructed by the State Department and Pentagon. Mullin’s hold on Donahue’s promotion follows the Senate’s approval of promotions for hundreds of other ranking military officers last week, The Washington Post reported.

President-elect Donald Trump has vowed to dismiss all senior Pentagon officials involved in the chaotic Afghanistan withdrawal, which led to the deaths of 13 American service members, the loss of billions of dollars in military equipment, the takeover of U.S. military sites by the Taliban, and the release of thousands of prisoners, many with terror ties.

In contrast, the Biden administration did not remove any senior military leaders in the aftermath of the withdrawal, despite significant security failures that claimed the lives of American soldiers and hundreds of Afghan civilians.

Lt. Gen. Christopher Donahue told military investigators that he joined U.S. forces in Afghanistan during the final days of the withdrawal, receiving orders to deploy to the country on August 16, 2021. The withdrawal concluded on August 30, with Donahue departing on the last plane out of Kabul.

In a statement to The Washington Post, the Pentagon emphasized Donahue’s qualifications and experience.

“His appointment comes at an extremely critical time in the European region,” spokesman James Adams said. “We urge the Senate to confirm all of our highly qualified nominees. Holds on our nominees undermine our military readiness.”

Although Democrats retain a majority in the Senate, a single senator can delay military promotions. Republican Sen. Tommy Tuberville of Alabama previously blocked hundreds of military promotions in 2022 and 2023 to protest a Pentagon policy that covers travel expenses for service members seeking out-of-state abortions.