“Jerry Falwell Jr’s ongoing behavior is appalling,” Rep. Mark Walker, the vice chair of the House Republican Conference, wrote in a tweet on Thursday that called for Falwell’s resignation.

The North Carolina congressman, a former pastor, said he serves on a music faculty advisory board at Liberty University and previously served as an instructor at the school. He has announced his retirement from Congress this year, after his district was substantially redrawn, but is considered a possible future Senate candidate.

“I’m convinced Falwell should step down,” Walker said. “None of us are perfect, but students, faculty, alumni and @LUPraise deserve better,” referring to the university’s gospel choir.

Walker’s tweet is the most high-profile condemnation of the photo of Falwell since it began circulating on the internet earlier this week.