If Republicans make significant gains in Senate races Tuesday, then politics will be following pattern. Presidents who are elected by big margins initially and then re-elected comfortably tend to have a lousy time of it in their sixth years.
Ronald Reagan won big in 1980 and won bigger in 1984. He had the Senate with him until 1986, but then the Republicans lost it—bad. Democrats picked up eight seats and took the chamber.
Dwight Eisenhower won big in 1952 and won big in 1956. He had a Republican Senate on and off through much of his tenure, and even the when the Democrats were in charge the margin was close. Then came 1958. Democrats picked up a remarkable fifteen seats (including two from the new state of Alaska). They also secured an overwhelming 283-153 majority in the House of Representatives.
If Republicans pick up the six seats they need to secure clear control of the Senate tonight—or after runoff elections in Louisiana and Georgia—that will be big news. But the real question is what happens with the governorships.
In a wave election, the party that wins big in congressional races also wins big in the states. That’s what happened in 2010, when Republicans took the US House, shifted plenty of Senate seats and made big gains in statehouses. That’s also what happened in a number of historic wave elections.
But will it happen tonight?
It could. According to the Real Clear Politics “poll of polls” assessment of recent surveys, fourteen gubernatorial races—including contests in battleground states such as Florida, Maine, Michigan, Pennsylvania and Wisconsin—are ”toss ups.” (That compares to eight “toss ups” in Senate contests.)