Rick Perry isn’t even in the race yet, or at least not officially, but he’s already within five points of Barack Obama in a head-to-head matchup.

So says Rasmussen Reports, which polled Perry, Michele Bachmann and Mitt Romney against Obama and found the president struggles to get more than 45 percent of the vote against any of the three.

Obama does best against Bachmann, whom he leads by a 46-39 margin. Against Perry, he leads by only 44-39. And against Romney Obama actually loses by a 43-42 margin.

An incumbent who gets between 42-46 percent against the three major challengers is a dead incumbent, electorally speaking. Any one of the three could beat him so long as the election becomes a referendum on the president’s fitness for re-election.

The real story, though, is Perry. He’s not even in the race yet. What happens to his numbers when he actually gets in?