House Speaker Nancy Pelosi has conjured up plenty of old ghosts since launching the health care fight back in July, invoking Democrats who laid the foundation for this year’s push — like Franklin Roosevelt and Harry S. Truman.

In a way, those titans came up short. Pelosi owes her current place on the cusp of a historic health care vote Saturday to far more anonymous contemporaries, like New Jersey Rep. Robert Andrews and California Rep. Xavier Becerra, whom Pelosi sent out to get the votes.

The fate of the bill itself rests on the shoulders of a new generation of Democrats whose young careers will be defined, in part, by the votes they cast Saturday — votes sure to be used against many of them in 2010...