Elizabeth Warren privately telling friends that she won't run if Hillary's in the race

Not that there is such a thing: Ms. Warren herself was not here, and she has repeatedly stated in public that she is not running for president. In private, according to several Democrats who have talked with her, Ms. Warren, 65, has also indicated that she would not challenge Hillary Rodham Clinton.

Liberals may be unhappy with the prospect of an inexorable march by Mrs. Clinton to the nomination a year and half from now, but at the moment they have no Obama-style candidate to challenge her and no clear-cut issue like the Iraq war to attack her over. They also face a front-runner who is far better positioned now with her own party than she was at the outset of the presidential campaign she saw slip away in 2008.

While Ms. Warren’s style of populism is certainly ascendant among Democrats, in the absence of a viable messenger to carry the progressive banner, it is a political current that Mrs. Clinton can move to co-opt.

“She has an unrivaled status in the party that was much less clear in 2006, when, after all, not only was Obama thinking of running, but there were a lot of credible candidates already running for president,” said David Axelrod, Mr. Obama’s former strategist, who has been somewhat critical of Mrs. Clinton recently.