It won't work. The tensions between McCain and Romney were nothing like the sheer hatred between the Clinton and Obama camps and Romney is much more gracious than Hillary.
Romney's deflected these preemptive attacks pretty well from Colmes on Fox. "On the major issues, I agree with him [McCain]" Romney said. He mentioned free trade, offshore drilling and low taxes.
"And I agree with him teh biggest threat to our security is radical, violent Islam and you don't even hear about that from the Democrats," Romney added.