I have a feeling Romney is using the LDS church to run a very effective campaign. I would suspect that they spend their church time going over campaign materials and how to get out the vote. That's 5.6 million people nationwide. If each of them went out and got 4 more voters for Romney, that's over 20 million votes and more then enough to win the primary.
If you could catch them doing that I'd love to hear about it.
So would the IRS as it would cost their church it's tax exempt status.
Edit to add: Same thing goes for any church doing something similar for Gov. Huckabee, or even Sen. McCain.