Ain’t going to happen.
The only chance is to get one of them to drop out and go head to head.
And then one (Newt or Santorum) needs to start winning every state back to back to back. No matter where. So even if Romney picks up delegates he would a.) lose his frontrunner tag and b.) lose his argument for nomination (You going to nominate a guy who lost the last 20 or so states?)
And then heading into the convention, if say Newt went on a huge run at the end, winning like 85-90% of the states - who you going to make your nominee? It will be a serious battle.
That’s the only chance. IMO.
The liberals who control the GOP want you to think having the nominee decided before the convention is a good thing. But that way, the reality is, the nominee is decided by manipulation of primary rules and attack ads funded by big-money interests (which are the GOP liberal establishment interests).
The result of the nominees being decided in the GOP-e way has been - Nixon, Ford, Bush, Dole, Bush, McCain - and the vice-presidential nominees are a sop to conservative base.
The only chance for the conservatives is for the convention system to be made to work as designed - that is, for delegates to be elected as representatives of their districts and go to the convention with the latitude to exercise their best judgement in selecting a ticket to represent the party in the general election.
THAT is the only chance. JMHO.