Feinstein just the latest example of an old problem: Politicians have long been able to evade questions about their ability to serve

Sen. Dianne Feinstein, in a wheelchair as she returns to the Senate after a more than two-month absence, May 10, 2023. AP Photo/J. Scott Applewhite

California Democratic Sen. Dianne Feinstein recently returned to the Senate after an almost three-month absence that – because she could not vote remotely and the Senate is closely divided – left the Democrats’ agenda in limbo.

Feinstein turns 90 in June and can barely walk on her own, and her mental acuity has been in question for many years. Yet she is holding on to her seat and won’t resign despite fervent pleas from some within her party.