MADISON, Wis. (AP) -- The four Democrats vying for a shot at unseating Republican Gov. Scott Walker in a recall election are set to clash in a debate at the University of Wisconsin-Madison.

Tom Barrett, Kathleen Falk, Kathleen Vinehout and Doug La Follette all are expected to appear at a Wisconsin Public Television debate Friday evening. The debate will mark final go-round between all four candidates ahead of Tuesday's primary. The winner will advance to face Walker in the June 5 general recall election.

Democrats have forced Walker and five other Republicans into recall elections as punishment for passing a contentious law stripping most public workers of their union rights. Democrats, though, have worked over the last few weeks to turn the election into a referendum on Wisconsin's sputtering economy.