(CNN)Wisconsin's Republican Sen. Ron Johnson announced he was running for reelection on Sunday. That should be viewed as good news by Republicans, who need a net gain of just one seat in this year's midterm elections to wrestle Senate control from the Democrats.

While we don't know what the outcome of this year's elections will be, history suggests that Johnson is likely to win and Republicans will not lose any of the seats they control to Democrats. Why? Because the opposition party rarely loses Senate seats in midterms when those states had leaned toward them in previous presidential elections. Let's start with Wisconsin. President Joe Biden won it in 2020, but only by 0.6 percentage point. He won nationally by 4.5 points. In other words, the state voted nearly 4 points to the right of the nation............