Democrats are certain to lose seats in the midterms. But how many – and why?

‘Democrat losses with working-class voters seem likely to continue apace.‘ Photograph: Chip Somodevilla/Getty Images

In the Abrahamic religions, there is a profound mystery in how to reconcile belief in free will with faith in divine providence. Similar mysteries lie at the heart of political science.

For instance, over the past 45 years, every time there has been a change of party in the White House, the opposing party won the governorship of Virginia a year later.