Barron had faced resistance from Democratic and Republican senators in recent weeks because of his involvement in drafting memos on the legality of drone strikes when he worked in the Office of Legal Counsel at the Justice Department in the early days of the Obama administration.
A group of liberal and conservative senators had said they would fight the nomination unless memos he wrote on the legality of drone strikes were made public, while others from both parties had called for the release of all memos Barron and others wrote on the subject. The White House allowed lawmakers to view copies of the memos Barron wrote last week in a secure Senate room.
The vote on Barron came a day after the Washington Post reported that the Justice Department will publicly release a secret 2011 memo, co-authored by Barron, that provided legal justification for killing American terror suspects overseas. The department informed the White House on Tuesday that it would not appeal a court order requiring disclosure of the memo.
On Wednesday, the liberal senators who expressed concern voted to proceed with Barron's nomination, while all Republicans present voted against proceeding. Beyond writing memos justifying drone strikes against American terrorism suspects abroad, Republicans are opposed to his nomination because of his liberal viewpoints.
In addition to the Republicans, two Democratic senators -- Joe Manchin III (W. Va.) and Mary Landrieu (La.) -- voted against proceeding. Spokespeople for the senators didn't immediately return requests for comments.