MADISON, Wis. (AP) -- The candidate Wisconsin unions want to take on Republican Gov. Scott Walker in a recall election offers a stark contrast to the union-busting son of a minister who has emerged as a national conservative hero.

Kathleen Falk has the backing of traditional Democratic supporters and Wisconsin's largest public unions, which are trying to knock out Walker after he effectively ended collective bargaining for nearly all public workers last year.

But despite the backing, Falk doesn't have a clear path to taking on Walker.

Democratic Milwaukee Mayor Tom Barrett, who lost to Walker in 2010 by 5 points, got into the race on March 30, more than two months after Falk. The unions don't like Barrett and urged him not to wade into the recall fight, but he did anyway.