The one candidate who could still challenge Clinton (but probably won’t).

Jonathan Bernstein gives (and Ed Kilgore endorses) plenty of reasons to think that it will be hard for any Democrat to challenge Hillary Clinton for the nomination. Both focus on the actions of the party elites—broadly understood—who decide the nomination. Ed notes that the analogy of 2008 is inapt, since at this stage back then Edwards had made tremendous organizational progress and Obama commanded universal fame and a unique ability to build up quickly. A couple of days ago Nate Silver noted that Clinton is very popular among Democrats of all ideological tendencies, and has racked up an unprecedented number of endorsements from Democratic members of Congress, again from across the party spectrum. But Jonathan has the most exhaustive list of what seriously running for president takes:

During the invisible primary, potential candidates introduce themselves to party actors and demonstrate their fealty to the party’s policy positions, their capacity for running a national campaign and the skills and abilities that promise to make them reliable presidents. They also begin to demonstrate that they can attract enthusiastic support from party voters (before the actual primaries and caucuses), and that they would make solid general election candidates. But not all candidates begin at the same starting line. Hillary Clinton had already achieved pretty much everything on the 2016 nomination checklist by November 2012. By contrast, Massachusetts Governor Deval Patrick, and Maryland Governor Martin O’Malley, have a lot more to do. The more a candidate must achieve, the more time it will take to do it.

This all sounds completely right. Any Democratic candidate jumping in at this point will have to have already demonstrated party loyalty, actual or likely executive skills, and the ability to win a majority of votes in both a party primary and a general election. Moreover, it would help if that candidate had a record of early and loud opposition to doing “stupid [stuff]” in the Middle East—the same issue that sank Hillary in 2008, and that deserves to sink her now—and a history of running, long before Elizabeth Warren, as a candidate of “the people” against “powerful forces.” It would help if the candidate had vast personal wealth, maybe not enough to self-finance a whole campaign, but enough to buy a campaign infrastructure and the advertising to compete immediately in early primary states, as well as strong and deep connections to Silicon Valley, the only serious rival to Wall Street (Clinton’s base) as a source of campaign cash. It would help, morally if not politically, if the candidate were universally regarded as caring fervently and persistently—as Clinton palpably does not—about the biggest issue of our time, global warming. Finally, it would be great if the candidate had a demonstrated willingness to tick off both Clintons, and were old and accomplished enough not to care about the future consequences of doing so if the challenge failed—though let’s say not too much older than Hillary Clinton, or a tiny bit younger.

No, I don’t have any evidence that Al Gore has any interest in coming out of political retirement; I see as of a few minutes ago that he has more interest in suing Al Jazeera (though that would hardly hurt a campaign). But if he did, and if he ran as the anti-war and populist—yet impeccably mainstream—candidate that Hillary clearly is not and has no desire to be, things would suddenly get interesting. And if he’s not, they won’t.