Nate Silver thinks the Republican race needs to remain divided in order for Ron Paul to play spoiler:
As the “third wheel” in a Romney-Perry or Romney-Gingrich race … Mr. Paul would potentially have more influence. I do not personally see a path wherein Mr. Paul wins a majority of delegates, but he could certainly control a substantial enough minority to become a power broker at the Republican National Convention, something that is an explicit goal of his campaign.
Nearly every part of the Republican primary process and, indeed, the party’s overall structure gives a massive advantage to people who have run before. The lack of super-delegates (ex officio convention delegates), for example, means that simply becoming well-known in the national media and among national figures conveys much less advantage than it does in Democratic contests. Republicans’ relatively greater reliance on low-dollar direct mail donations, likewise, means that having a well-tested list from a previous run for office conveys a fundraising advantage. Even the structure of grass roots groups on the Right conveys an advantage to those who have run before: the single greatest source of on-the-ground manpower on the Left, unions, are national organizations with top-down structures while the churches, community organizations, and tax reform groups important on the right are rarely centralized. And some right-of-center groups that have central structures–Americans for Prosperity, for example–don’t directly engage in electoral politics.