While the Democrats battle extremes within their party in tomorrow’s recall primary in Wisconsin, Governor Scott Walker faces his own challenge in the Republican primary.

Arthur Kohl-Riggs, a 23-year-old self-described “progressive Republican” who dresses like Abraham Lincoln and frequently appears at rallies around the state, is on the Republican primary ballot along with Walker.

I came across Kohl-Riggs at a union protest of the the Tax Day Tea Party in Wisconsin, where he was closely guarded by a minder during his interviews. Kohl-Riggs told me that he believes Scott Walker is a “fake Republican”:

I absolutely deny the idea that Abraham Lincoln would acknowledge Walker….

While Kohl-Riggs, who has written for The Progressive, appears to be of little threat to Walker, it is possible for Wisconsinites to vote (no, not that way) for candidates in both parties tomorrow. This leaves open the remote possibility that Kohl-Riggs could knock Walker off the ballot:

For the first time in recent memory, Wisconsin voters on Tuesday will be able to vote for both Republican and Democratic candidates on the same ballot.

Typically, voters in a primary election in Wisconsin must choose candidates from the same party for all offices up for election. However, the recall elections for governor and lieutenant governor have led to a unique situation in which primary voters can cross party lines to vote for each office.

“The difference is that each of these recall primaries is a separate event that just happen to be occurring on the same day,” explains Reid Magney, a spokesman for the Government Accountability Board. “There was a separate recall petition filed for each of these officeholders.”

To be clear: Voters can only vote for each office once. That means they must choose to vote in either the Democratic or Republican primary for governor, and they must also choose whether to vote in the Democratic or GOP primary for lieutenant governor.

Republicans in Wisconsin ought to consider this potential outcome when deciding whether to vote in the primary tomorrow. Kleefisch, who has not been challenged by another Republican, is being subjected to recall on the June ballot.