As you can easily see, Cain's numbers are falling because he seems to flounder on issues like abortion and foreign policy. Perry's popularity is taking a huge hit because of his stance on immigration and the HPV vaccine mandate. That leaves Romney.
The problem with Romney is that his numbers do not change, even as the others go down in flames. This is because most Republicans are not happy with Romney, never have been and never will be, thanks to his ultra-moderate positions and flip-flopping. RomneyCare is too much like ObamaCare
Meanwhile, all the pundits seems to be overlooking that Gingrich is slowly, steadily gaining in the polls. He picks up many of those who are abandoning Cain and Perry because they see Gingrich as extremely intelligent (he is), a man who is not so quick to attack other Republicans (he isn't), and a man who actually offers specific solutions to specific problems (he does).
I don't know if Gingrich will be "the last man standing" because I do not know if there is enough time left to stand out (some states are pushing their primaries and caucuses ever earlier on the calendar) or if he has enough money to succeed.
I do know he has the intellect, leadership ability, and solutions we need. But in today's fast-moving world, I'm not sure that is enough. Too bad.