Hint: He's in the Republican Party, not in the Democratic Party. He could win the Republican nomination with the hardcore base of the party and the tea party. He would undoubtedly have a more difficult time in the general election when you throw in Democrats and, especially, Independents who are disgruntled with the current administration. Anyway, this is all pretty much a moot point because it's looking like Mitt Romney will win the nomination.
Of course, the GOP 'establishment' should take a stand against those people and abolish primaries altogether. That way, the Republicans would be more likely to have decent candidates in a similar mould to Eisenhower, Nixon, Rockefeller, Goldwater etc.