The current realignment of US politics means that the outcome in November could be anyone’s guess.

May has been a pivotal month in the US presidential election; it has seen the continued success of Donald Trump in the Republican Party’s presidential primary, and his ascension to become the party’s likely presidential nominee. Walter Dean Burnham writes that Trump’s victory, and to an extent, the success of Vermont Senator Bernie Sanders, have been part of another realignment of US politics, one which has left many in both parties completely at sea.