Sen. John Fetterman could remain hospitalized for more than a month as the Pennsylvania Democrat undergoes treatment for depression, a senior aide said, following a series of health setbacks.On Wednesday, Mr. Fetterman checked himself into Walter Reed National Military Medical Center, the second hospitalization for the freshman senator in recent weeks. His office said that Mr. Fetterman has experienced depression off and on throughout his life and that the senator voluntarily entered the hospital after consulting with the attending physician for Congress, Dr. Brian P. Monahan.A senior aide to Mr. Fetterman said in an interview late Friday that the senator will remain hospitalized as doctors try out new medications and dosages to test their efficacy. Mr. Fetterman will also engage in talk therapy, the aide said, meeting with a professional therapist to discuss the experiences he has had, including the challenges of campaigning for office.

The hospital stay could range from weeks to more than a month, but likely less than two months, the aide said, citing the time frame the doctors are focusing on.

The aide said that Mr. Fetterman had gone to George Washington University Hospital due to being malnourished and dehydrated, and those problems re-emerged in the past week.

“There’s a lot of absorbed negative experiences from [the campaign] that are probably worth unpacking in a therapeutic environment,” the aide said.

Lawmakers have rallied around Mr. Fetterman. “Seeking help when you need it is a sign of strength, not weakness, something that John is demonstrating for all of us,” tweeted Sen. Tina Smith (D., Minn.), who has previously detailed her struggles with depression.