McCallum's polls have been up and down. Currently, he is holding his own. President Bush is in town this week for a McCallum fund raiser. The hope is the Dems kill each other in their 3 or 4 way primary. McCallum has been running lots of radio commercials since the start of the year on current state related topics. Recently, he has one running with a strong endorsement from President Bush. Polls won't mean too much until after the Dem primary in September and it becomes one-on-one.
Conservatives give mixed reviews to McCallum. And Tommy Thompson's brother, Ed, is running for governor on the Libertarian ticket. My guess is that faced with a structural budget deficit in the next few years, and with taxes already about the highest in the country, most will come around to backing McCallum this fall, out of sheer self-preservation.