In the wake of the 2012 elections, Republicans are being warned once again that they need to compromise their principles to win at the ballot box. That the only way to win the center is to move to the center.

If this were true, Barack Obama would not be president today—and I would not be governor of Wisconsin.

When I was first elected as Milwaukee County Executive in 2002, pundits said it was a fluke—a Republican elected in a heavily Democratic district in a special election in the wake of a political scandal. To stay in the job, they said, I would have to move to the middle. Instead, I governed as a conservative reformer and won three consecutive elections as county executive, each one by bigger margins. The last one, in 2008, was especially noteworthy. Mr. Obama won Milwaukee County with 67.5% of the vote; I won with nearly 60%.

As governor of the state, my administration reformed collective bargaining in the public sector against enormous odds, turned a $3.6 billion deficit into a $760 million surplus, and cut taxes. In response to the union reform, opponents mounted a recall election in 2012. It was contentious—yet after enduring a hundred thousand or more protesters and tens of millions of dollars in negative ads, we won the recall by a bigger margin than in the gubernatorial election in 2010.

And here is where the results get intriguing: Exit polls showed that roughly one in six voters who cast their ballots for me in the June 2012 recall also planned to vote for Mr. Obama a few months later. These Obama-Walker voters constituted about 9% of the electorate.