The Gentleman said:
Of the early primaries, Ron Paul can only win Iowa. And while his positions were distinguishing in 2008, the only marked difference between him and the other candidates is foreign policy, which is essentially an isolationist policy that is not attractive to the GOP's pro-military base.
Although I know to actually win primaries other than Iowa shall bode a challenge to Paul, I do challenge your assertions on his domestic and foreign policy; all the other Republicans advocate a more centrist approach- none oppose the federal reserve, for example- and some don't even cite the tight regulations that Paul wishes to be done with, and many don't even go towards the radical tax cuts he wishes.
Also, Paul's foreign policy is not "Isolationist"- it's non-interventionist. He just doesn't want US forces in other nations, abusing their sovereignty and committing scores of unethical acts against them; he believes in trade and negotiations as a diplomatic tool, not threats and violence. That's not isolationism, he wants to do business with the world.
And yes, many mainstream Republicans don't like Paul. But remember this "Blue Republican" movement, and the hardcore Paulites who've been in the party and rooted for him for years.