If he tries for it, I think a TRUE CONSERVATIVE with credentials should challenge him for that Constitution Party nomination, I am sure he or she could take care of Paul in no time flat, if organized and name-brand, with experience and a national following. Some names come to mind.
Name away.
I think that this election could be a golden opportunity for the Constitution Party or another conservative third-party to get a foundation built. If the Republicans nominate Giuliani or Romney, there will be a large number of disillusioned Republicans who might look at a third party. Giuliani could alienate many pro-lifers who might give up on the Republican Party for good. Romney's Mormonism is going to be a tough sale among the evangelicals, his conversion on abortion is not trusted by pro-lifers, and his Hillary-like health care plan is not going to be popular with conservatives.
To possibly capitalize on this, the CP is going to have to come up with a reasonable candidate, not a nut-job like Ron Paul. I'd be interested in hearing the names you're thinking but the first one that popped into my mind was Rick Santorium.