WASHINGTON--Polls show GOP White House hopeful Rick Santorum has a good chance of winning the Michigan primary at the end of the month, polls show, an upending prospect for chief rival Mitt Romney, a Michigan native--and son of a Michigan governor.

Santorum--who will be outspent by millions of dollars by Romney's campaign and the superpacs backing him--produced a humorous spot about Romney throwing mud all over Santorum. In Detroit today, Santorum delivers a speech before the Detroit Economic Club.