In a strong year for Republicans, adding moderates from the Northeast and Midwest makes sense, says former Bush White House spokesman Ari Fleischer, because those are historically where the moderates have come from.

In the 100-seat Senate, “we’re at decimated levels now, at 41, so if we’re rebuilding, those are the most likely regions,” Mr. Fleischer says.

Come January, “it’s possible that we could have a more moderate Senate, because of some of the new people, but also because of the general political dynamics that would then be in place,” says Cal Jillson, a political scientist at Southern Methodist University in Dallas.