(The Hill) – The blockade from Sen. Tommy Tuberville (R-Ala.) on about 250 of the Pentagon’s general and flag officers has left the Marine Corps without a confirmed leader for the first time in 164 years.

Marine Corps Commandant Gen. David Berger officially retired on Monday, leaving Assistant Commandant Gen. Eric Smith as the acting commandant and leader of the military branch until he is confirmed in the Senate.

The last time the Marine Corps was left with an acting commandant was in 1859, when Archibald Henderson, the fifth commandant of the Marines, died at 76 without a successor in place.

It’s unclear when Smith could be confirmed. Tuberville’s hold on the Pentagon nominees, which he began in March to protest the Defense Department’s new abortion policy, shows no signs of weakening, even as the block has sparked bipartisan frustration.

Tuberville’s hold is affecting leadership posts held by key military officers, prompting concern from the White House, Defense Department, former Defense secretaries under Republican and Democratic administrations and congressional colleagues, all of whom have warned about the harm to national security from the block.

The hold is also set to block key nominees on the Joint Chiefs of Staff, including the replacement for Gen. Mark Milley, the chairman, who retires in September.

In an opinion article, Tuberville argued his block does not affect national security and is “not affecting readiness.”

“Acting officials are in each one of the positions that are due for a promotion,” Tuberville wrote last month in The Washington Post. “The hold affects only those at the very top — generals and flag officers. The people who actually fight are not affected at all.”

Tuberville is protesting the Pentagon’s abortion policy because it provides paid leave and reimbursement costs for travel for servicemembers who cross state lines to get an abortion. The senator says it violates the Hyde Amendment, which prohibits federal funds from paying for abortions.

Republicans have reportedly suggested an off-ramp to Tuberville, but the senator says he will only lift the ban on two conditions: the policy is formalized in law or dropped.

“If Democrats can’t pass legislation to authorize the abortion policy, then it shouldn’t be the policy,” Tuberville wrote in his opinion piece.