How the path to the Democratic presidential nomination is different in 2020

The Democratic Party will officially nominate a 2020 presidential candidate at its convention next July, but not before a long primary season that kicks off with the Iowa caucuses in February and ends with the Puerto Rican primary in June.

The goal for candidates: Amass on a state-by-state basis the 1,885 delegates needed to be nominated on the first ballot at the convention in Milwaukee. A candidate must get at least 15% of the vote statewide or in an individual congressional district to be awarded delegates.

The nominating contest will...