Anything is possible, but looking at the primaries with any hope at this point is difficult because Romney only needs a small percentage from here on out to arrive at the 1144. Even the conservative states have given him 30% of their votes and now that Santorum is out and Gingrich is out of compaign money there is little to do in the Republican party.
Not true, he needs about 46% of the delegates in the remaining 20 states. That's not a small amount. So it's certainly within the realm of possibility that his support gets knocked a little further down to that level from where it is now. He's only won over 50% of the popular vote in 3 out of 30 states where everyone was on the ballot so far.