MUSKEGON, Mich. (AP) -- Republican Rick Santorum is drawing enthusiastic crowds in rural Michigan ahead of Tuesday's important presidential primary in Michigan.

But rival Mitt Romney, who grew up outside Detroit, is counting on his huge political network to deliver the victory he needs to solidify his position as the GOP front-runner.

Santorum has few organizers or volunteers helping him in the state, and that's putting him at a disadvantage in getting his supporters to the polls.

By contrast, Michigan governor, legislative leaders and seven of the state's nine Republican congressmen have endorsed Romney and they're helping with campaign rallies, phone banks and get-out-the-vote efforts.