In the last week, there appears to be a move in Rasmussen national tracking polls in favorable/unfavorable ratings of Barack Obama. In a week, he has gone from about a 52% favorable / 45% unfavorable rating last week to a 47% favorable / 51% unfavorable rating on April 16, i.e., from a 7% plurality to a 4% deficit. McCain's ratings have not changed much (on April 16, he has a 55% favorable and 42% unfavorable rating).
It is too soon to tell whether this movement is lasting, but if it is, Obama's recent problems may affect the general election more than the Democratic primaries, where his overall numbers do not seem to have deteriorated at all in most polls.
BTW, both McCain and Obama have better favorable / unfavorable ratings than Clinton.