In the case of Kahl, without Manchin’s vote, Biden would need a Republican senator to support the candidate in order to confirm him in a 50-50 Senate.
Manchin did not attend Kahl’s confirmation hearing last week, giving no public indication of his position on Kahl. His office did not immediately respond to a request for comment.
A defense official confirmed that a phone call with Manchin was on Austin’s schedule for Tuesday, but did not provide details about its content.
Senate Republicans attacked Kahl at the Armed Services confirmation hearing last week by tweets criticizing the policies of former President Donald Trump and Republican lawmakers. The tour was by far the most controversial so far for a Pentagon Biden nominee.
Several members of the Republican Party declared during the hearing that they would vote against Kahl, citing his rhetoric and views on Middle East policy, including his defense of the 2015 nuclear deal with Iran.
Alex Thompson contributed to this report.