Ross Douthat gets a bit carried away in his column on Hillary Clinton:

And her desire converges almost perfectly with the interests of her party, even if not every liberal quite realizes it yet. That’s because Clinton’s iconic status is, increasingly, the only clear advantage the Democratic Party has. If her position is weakened, diminished or challenged, the entire coalition risks collapse.

It’s true that Democrats would presumably prefer to have their likely nominee to remain as popular as she seems to be right now, but that isn’t going to happen. Clinton’s favorability is bound to decline once she returns to the fray as a partisan politician, and there’s no way to prevent that. It would be a mistake to assume that a Clinton nomination that faced no serious and determined challenge from others in her own party would be the best one for the party’s chances in the general election. I don’t see any likely challenger capable of depriving Clinton of the nomination, but the Democrats would almost certainly benefit from having one or more candidates make the attempt. Like Romney in the last Republican contest, Clinton appears dreadfully inevitable with built-in advantages in name recognition, fundraising, and support from party leaders, and unlike Romney her party’s voters genuinely seem to like her. Even so, if she faced no meaningful competition and no serious criticism while coasting to the nomination, it would very likely depress turnout in the general election and it would encourage complacency and a sense of entitlement in a Clinton crowd that is very susceptible to both.

The Democratic Party has long been “a sprawling, ramshackle and heterogeneous arrangement,” but that hasn’t stopped it from winning the popular vote in five of the last six presidential elections. It cobbles together majorities by being “sprawling” and “heterogeneous,” and doesn’t depend on a particular nominee to do this. The extremely narrow margin of Bush’s re-election in 2004 points to this. Democrats have a coalition of competing, sometimes opposing interest groups and constituencies, but then they usually don’t pretend to be anything other than that. One of the stranger conceits that many Republicans have about their party is that it is a so-called “real party”: it supposedly represents some coherent set of beliefs that makes it substantially different from being an “incoherent amalgam” of interest groups. Perhaps because Democrats don’t try to paper over the contradictions and tensions in their coalition as much, they are able to appeal to a wider variety of voters than their opponents. The Democrats might be slightly less likely to win the general election without Clinton, but all thing considered they are probably still going to have the stronger and more quickly-growing coalition no matter who their nominee happens to be. If Clinton chose not to run for some reason, that coalition wouldn’t be at any real risk of dissolution.