Zogby is right, of course.
If it’s just Cain versus Romney, then Romney tops out at 35% of the vote (at best), and loses. But with spoilers still in the race (mainly Perry, but Newt to some extent), it stays close.
If I were Romney, I’d be encouraging Perry to fight the big fight every day...and no doubt his bunch is doing just that.
Romneycare’s 35% top out was months ago.
The only way he can get close to that again is if Perry drops out.
Perry’s less than 10% remaining are the open borders crowd and they will probably all go Romney.