The Huckster would assure a 40 state Democrat sweep. A Romney win might actually give Fred a shot in South Carolina so the Dumbocrats aren’t thinking about the next move.
They don’t want their supporters to vote for Romney because they view him as the weakest candidate. They want the Republican candidates to continue their battle, trashing each other and using up resources in their primary battles.
If Romney wins Michigan, that will give a winning state to each of the top three: Huckabee in Iowa, McCain in New Hampshire, and Romney in Michigan. This will keep them battling. If McCain or Huckabee win Michigan, Romney may pull out.