[Ed. – Everyone who says this speaks as if we are in a “normal” political time. It should be blindingly obvious that we are not. To use Barone’s expression, “special circumstances” are exactly what we have today. Trump defied all the prognostications in 2016. The GOP has handily won every special election that mattered to the “Trump” calculus in the months since. If 2018 is a referendum on Trump, it’s the Democrats whose chances are slim.]
Curious fact, and one disquieting for Republicans looking ahead to 2018: In the past 65 years, starting with 1952, the president’s party has managed to win a majority of seats in an off-year election only four times. In the other twelve off-year elections, the opposition party won a majority.
Special circumstances, unlikely to be replicated next year, accounted for the four presidential party victories. …
Yes, Republicans won 241 House seats in November 2016 and have held on to the four up for grabs in the special elections this spring, and they’re unlikely to lose the one currently vacant seat, in Utah, in the special election next fall. But unlike the Democrats in 1966 and 1978, who could have lost 70-plus seats and still kept a majority, Republicans will lose theirs next year if they lose a net of only 24 seats.