Mr. Waller, a regional Fed research official, had been up for Senate confirmation alongside Judy Shelton, whose long-held preference for some type of gold standard and apparent skepticism of Fed independence hurt her chances of confirmation.
Mr. Waller made it through, but just barely, with a nearly party line vote of 48 to 47.
Senator Rand Paul, a Kentucky Republican, joined Democrats in voting against Mr. Waller.
The board will have one remaining open slot if Ms. Shelton is not confirmed.
The White House announced that it would tap Mr. Waller and Ms. Shelton in mid-2019, but their nominations — long treated as a pair — faced a roller-coaster confirmation process as senators grappled with misgivings over Ms. Shelton.
WASHINGTON, Christopher Waller, Trump, Joseph R, Biden, Waller, Judy Shelton, Rand Paul, Jerome H, Powell, Shelton, Mitch McConnell
Federal, of Governors, Kentucky Republican, Mr, White House