Still, for the sake of argument, let’s say that the American economy will gather momentum, and that by the fall, most of the public—heretofore very skeptical after a long recession—is on board and optimistic (quite a leap, I know). Even in that case, could Democrats convert a hypothetically booming economy into an antidote to Obamacare unhappiness and sagging popularity for President Obama?

History is not encouraging. There is a remarkably weak relationship between the robustness of the U.S. economy and midterm election outcomes. The Senate results can be idiosyncratic, so let’s focus on the House to make the point.

First, as expected, bad economies nearly guarantee that the president’s party loses a substantial number of House seats. President Harry Truman’s experience in 1946, when GDP declined by nearly 12 percent and Democrats lost 55 seats, proves the point. So do Dwight D. Eisenhower’s 1958 midterm (-0.7 percent GDP, -48 seats), Gerald Ford’s 1974 midterm (-0.5 percent GDP, -48 seats) and Ronald Reagan’s 1982 midterm (-2 percent GDP, -26 seats).