Mitt Romney, Paul Ryan file photo

During an April visit to Milwaukee, Republican presidential candidate and former Massachusetts Gov. Mitt Romney appeared with House Budget Committee Chairman Rep. Paul Ryan, R-Janesville, a possible vice presidential running mate.

STEVEN SENNE - Associated Press

Generally, in Wisconsin, a person can only be a candidate for one office at a time.

For instance, U.S. Rep. Tammy Baldwin, D-Madison, must vacate her safe seat in the House to run in a hotly contested race for U.S. Senate.

Similarly, the two state legislators who now seek Baldwin’s House seat, state Reps. Mark Pocan, D-Madison, and Kelda Roys, D-Madison, must surrender their safe offices for a chance to serve in Congress.

(That’s why so many have expressed puzzlement at Roys’ decision to run against the better-known Pocan. Why give up an Assembly seat that she could hold for years to compete in a race that she has very little chance of winning?)

However, Wisconsin law does allow for one glaring exception to this rule. A candidate for president or vice president can run simultaneously for his current office.

Thus, U.S. Rep. Paul Ryan, R-Janesville, could be Mitt Romney’s vice presidential running mate as well as compete for his eighth term in Congress.

As Madison as it gets: Get Cap Times' highlights sent daily to your inbox

If Ryan were elected vice president, a special election would be called to fill his vacated congressional seat. The southeastern Wisconsin district Ryan represents, which includes Kenosha, Janesville and a number of Milwaukee suburbs, leans slightly Republican.

Due to Ryan’s name recognition and incumbency, the New York Times has rated his re-election bid against Democratic candidate Rob Zerban as a “safe Republican” win.

Rumors abound that Romney is considering Ryan as a running mate, among other conservative firebrands such as Florida Sen. Marco Rubio. However, poll numbers suggest that Ryan's outspoken advocacy for radically restructuring entitlement programs would hardly help Romney woo independent voters, and could hurt him among seniors.

While Ryan remains a possible candidate, the consensus seems to be that Romney will choose a less polarizing figure, perhaps in the mold of former Minnesota Gov. Tim Pawlenty.

Jack Craver is the Capital Times political reporter, focusing on elections, candidates and campaign finance.