Ambinder thinks Obama won't have a big effect on the midterms:
Obama's net effect on congressional races might just turn about to be a big "meh." As skeptical as white people are about Obama's policy agenda, enough still want him to succeed. So what's the best thing for Obama to do between now and November? Instincts will persuade the White House to send the president to campaign for Democrats in safe areas and selected television markets, hoping to spark Democratic enthusiasm. As the Bush White House learned, targeted interventions can move the needles, especially when the other party's get-out-the-vote machinery is in question.