Wave watch: It's Trump vs. the economy

Data: Historical changes in House seats from the American Presidency Project, approval ratings from FiveThirtyEight, and views of the economy from AGC Research LLC. Chart: Harry Stevens/Axios

Here's why it's so hard to predict whether Republicans will actually lose the House in November: It depends whether the election turns on President Trump's low approval ratings or the booming economy.

Between the lines: As this interactive graphic shows, the party in power tends to do well in the House during midterm elections when voters are happy with the economy, but it does poorly when the president's approval rating is low. There's no recent precedent in which the economy is doing well but the president's approval rating is underwater.