But the most compelling reason for them to step aside is generational. All three are technically from the so-called Silent Generation, but they are the vanguard of the baby-boom generation that dominates Congress. Pelosi has been emblematic of that generation’s governing style on both sides: Passionately ideological and unyielding, they presided over cultural warfare and dysfunction.

This is why Tim Ryan’s long-shot challenge to Pelosi is welcome. The 43-year-old backbencher from the Youngstown, Ohio, area won’t win, but he is doing Democrats a favor by forcing them to think about the desirability of keeping their septuagenarian leaders in place. Hopefully it will hasten their succession plans — Pelosi’s iron grip over the caucus has made this difficult — so that all three can step down soon. Among those Pelosi is grooming: Joe Crowley, 54; Linda Sánchez, 47; Joe Kennedy III, 36; Eric Swalwell, 36; Katherine Clark, 53; and Matt Cartwright, 55.

Ryan isn’t a flawless candidate. He’s only a recent convert to supporting abortion rights. His detractors point out that in his 14 years in the House, he has won passage of just three minor bills. Opponents grumble that his real purpose in challenging Pelosi is to raise his visibility for a gubernatorial run in 2018, when Ohio Gov. John Kasich will be term-limited.