A financial crisis in 2007 would have probably tilted the primaries to Hillary despite the defects in her campaign organization. OTL, the early contests were not fought over the economy but over things like the Iraq War. An earlier financial crisis would have raised the stakes substantially and made Obama's relative lack of experience with economics and the private sector a severe handicap. In fact, I might go so far to say that in the context of an ongoing financial meltdown, Obama's candidacy might well have descended into joke territory, as he had ZERO credentials for handling a major economic downturn. Moreover, the prospect of Bill Clinton, creator of the '90s prosperity, looking over Hillary's shoulder in the Oval Office would have been a plus in such an environment.
This, in turn, would have helped a Clinton presidency in a couple of ways. First and foremost, the bailouts of big banks and industry would have been clearly Bush programs and the recession-induced soaring deficits would have been clearly established on Bush's watch. That, in turn, probably means that the Tea Party never happens or, if it does, it remains relegated to the fringes of the Right.
On the GOP side, this probably helps Romney in the primaries, but any GOP candidate is probably dead meat in the general election owing to the severity of the crisis. The unknown here is whether Bush would have pushed for stimulus in 2008. If not, it could well be the case that the depth of the crisis in 2008 is worse than it was in OTL 2009 and that an incoming President Clinton faces a situation even worse than Obama did.