WASHINGTON — Sen. John Fetterman “will be back soon,” an aide said Monday, in releasing the first photos of the Pennsylvania Democrat since he checked himself into Walter Reed National Military Medical Center for clinical depression nearly three weeks ago.

In the photos, Ms. Fetterman and his chief of staff, Adam Jentleson, are seen seated together at a table in a bright hospital room, looking over some papers. Mr. Fetterman is wearing a hoodie and shorts, an outfit he would have typically been spotted in before he entered the Senate.

“Productive morning with Senator Fetterman at Walter Reed discussing the rail safety legislation, Farm Bill and other Senate business,” Mr. Jentleson tweeted. “John is well on his way to recovery and wanted me to say how grateful he is for all the well wishes. He’s laser focused on PA & will be back soon.”

Mr. Fetterman checked himself into Walter Reed on Feb. 15 to receive treatment for clinical depression. He has remained hospitalized since, with few concrete indications of when he would be able to return to the Senate.