Obama might have been the liberals’ choice in the 2008 primaries, but it wasn’t because he was the most liberal. It was because he embodied almost everything liberals wanted in a candidate, most of which had little to do with ideology. He was new and fresh, multiracial and cosmopolitan, and untainted by the compromises and cowardice Democrats saw their party gripped by in the previous decade.

Most of all, Obama made voters understand what a vote for him said about them. If you were an Obama supporter, you were supposed to be forward-thinking, creative, optimistic, courageous and youthful. (That was the genius, for instance, of hip-hop artist will.i.am’s viral campaign video.) It wasn’t too different from the marketing message that has worked so well for Apple, and after feeling beaten down for eight years, it was just what liberals wanted.

It’s possible that another Democratic politician could make people feel something like that again, even with the idealism of the 2008 Obama campaign ground down in the messy reality of governing. Some believed Elizabeth Warren could be that candidate, and no one has spoken more often or more eloquently about inequality in recent years than the Massachusetts senator. But Warren now says she isn’t going to run (though, of course, she could change her mind). There might well be a governor or senator out there who could emerge as a liberal champion, but if so, whoever it is is lying low at the moment.

If that serious challenger to Clinton does emerge, he or she is going to need to do a whole lot more than run to the former secretary of state’s left, because in presidential politics, ideological crusades almost always fail.