Because Wisconsin's election rules allow primary voters, regardless of party affiliation, to vote for candidates in any political party, there was much talk before the April 3 GOP presidential primary about whether state Democrats would cross over and cast a ballot for one of the GOP nominees. The thinking was that Democrats would vote for Rick Santorum, considered to the right of frontrunner Mitt Romney, in order to advance the more extreme - and therefore less electable - nominee to the November general election against President Barack Obama.
Isthmus design artist David Michael Miller decided to test the theory by mapping vote results for the primary. Sure enough, Santorum was the top vote-getter in Madison, including the most liberal wards around Olbrich Park and Williamson Street that netted Democrat Tom Barrett more than 90% of the vote when he ran unsuccessfully against Republican Scott Walker in the 2010 governor's race.
Romney won much of the rest of Dane County, including Verona, Fitchburg, Sun Prairie and Cross Plains. The exceptions were a few campus wards, where libertarian Ron Paul emerged victorious.