The Senate voted 49-45 along party lines to confirm Colin Kahl as under secretary of defense for policy following weeks of GOP opposition.
Kahl is only the third Senate-confirmed official President Biden has sent to the Pentagon, after Defense Secretary Lloyd Austin and Deputy Defense Secretary Kathleen Hicks, both of whom were confirmed by overwhelmingly bipartisan votes.
It was expected that Vice President Harris would need to cast a tie-breaking vote to confirm Kahl, but too few Republicans were present for the vote for that to be required.
Senate Republicans long sought to block Kahl's nomination, citing partisan tweets and policy statements, as well as the role he played in the former Obama administration's 2015 nuclear deal with Iran. Some Republicans also requested the FBI investigate Kahl for allegedly disclosing classified information on social media.
Kahl, who has denied revealing classified information, has pledged to be "nonpartisan" if confirmed, and has apologized for past tweets that may have been "disrespectful," including one in which he called the GOP "the party of ethnic cleansing."
"The last few years have been pretty polarizing on social media. I am sure there are times that I got swept up in that," he said during his March nomination hearing.