Sen. Dianne Feinstein away from Washington due to "health matter"

Sen. Dianne Feinstein is away from Washington, D.C., this week as she deals with a "health matter," a spokesperson for the retiring senator from California said. 

Feinstein announced last month that she won't be seeking reelection next year, but at 89, she still has nearly two years left in her current term. 

"The senator is in California this week dealing with a health matter," a spokesperson for Feinstein said. "She hopes to return to Washington soon." 

Feinstein has already missed multiple votes this week. Her spokesperson did not say what the health matter is or when she might return. NBC News first reported Feinstein's absence. 

She isn't the only Democratic senator who is away from Capitol Hill for health-related reasons. Democratic Sen. John Fetterman has been undergoing treatment for clinical depression. Pennsylvania Sen. Bob Casey underwent prostate cancer surgery in mid-February, but he has returned to work. The absences of Fetterman and Feinstein have meant that Vice President Kamala Harris had to break multiple tie votes this week.

It is very difficult for Democrats to pass major legislation or approve nominees along party lines with two senators absent. 

On Tuesday, White House principal deputy press secretary Olivia Dalton declined to comment directly on whether the administration is concerned Fetterman's absence could hamper the confirmation of Julie Su, President Biden's nominee to run the Department of Labor.

"Millions of Americans go untreated with depression every day," Dalton said. "Senator Fetterman did the right and brave thing by getting the help he needs. And we're grateful to Senator Fetterman for leading by example and taking the time he needs to get healthy."