Retired Army Gen. Lloyd Austin is Biden’s pick for Defense secretary, but the former U.S. Central Command chief falls three years short of the seven-year “cooling off period” for a former officer to take the Pentagon’s top civilian post. Lawmakers in both chambers would need to vote to waive that law for the Senate to proceed to his confirmation.

Among those who said they will vote “no” on the waiver are Sens. Elizabeth Warren, D-Mass., Tammy Duckworth, D-Ill., Richard Blumenthal, D-Conn., and Angus King, I-Maine.

Arkansas Republican Sen. Tom Cotton questioned whether Austin’s experience was the best fit for the Defense secretary role, but did not indicate how he would vote on the waiver. Others, including Sen. Tim Kaine, D-Va., said they were undecided.