Fear:
To win over the skeptical conservative base, [Romney] needs influential figures on the right to vouch for him. But if they vouch for him, they risk being declared RINOs themselves, establishment sellouts trying to force an impure nominee on the GOP. And they know that any dramatic gesture they make now will be remembered.
What if Romney wins the nomination, loses in the fall, and the conservative base concludes they were tricked again – that it’s time to redouble their purity crusade? Or what if Romney wins in the fall and, like George H.W. before him, tries to govern from the middle as president, prompting a GOP civil war. What conservative leader would want to spend the next four years explaining why he or she played such a critical role in elevating that kind of president?