Yglesias says Clinton still has some strength:
...the most recent poll of Ohio shows Clinton with a big lead, and considering the convincing nature of Clinton's wins in states like Arizona, Oklahoma, and California I think you need to assume she'll win there until we see some kind of poll offering clear evidence to the contrary. Obama's put together a string of impressive wins, but it's still the case that in the Democratic Party women outnumber men, whites outnumber blacks, working class people outnumber college educated professionals, and senior citizens outnumber under-thirties. Under the circumstances, Clinton continues to be in a strong position.
All salient points. But this is a campaign. Campaigns are dynamic. They have mood and momentum. On both, the Clintons are in more trouble than they have ever been in an election before (barring Bill's failed re-election as Arkansas governor).