Mitt Romney was never the frontrunner for the Republican nomination, his poll numbers apparently have a cap at around 25-28%, meaning the more conservative Republicans (Myself included) should represent well over 60% of the Republican electorate and should be able to easily elect a much more right leaning candidate than Romney. The following chart of poll numbers confirms how Romney's numbers have been stuck at 25 while numerous candidates have exceeded him at different times.
However, the fucking problem here is that there are way too many damn lines on that graph. Gingrich, Perry, Bachmann, Santorum, and to a much smaller degree Paul are all fighting over the exact same voters, fracturing the conservative vote and giving Romney a slight edge because he has a monopoly over the moderate vote. However, if it were just that, Romney would still lose because even with many candidates fighting over the conservatives, there has always been one candidate that manages to rally enough of them to gain an edge over Romney.
What the above poll shows, besides the aforementioned splintering of the conservative base, is Romney's lifeline to the nomination. While at the moment there is a considerable "Anybody but Romney" crowd, that movement will all but disappear if somehow Ron Paul manages to pull ahead. Holy shit do me and other mainstream conservatives hate this guy Ron Paul, who is a libertarian and has a random as fuck foreign policy that scares us all away. If he gains significant momentum and wins several states, all the remaining conservatives will ditch their preferred candidate and run their ass over to Romney in an attempt to stop Ron Paul from winning the nomination.