A contested Democratic convention, in which no candidate goes into the event with a majority of delegates, is more likely in 2020 than it has been at any time in decades. And several recent developments in the race have made the prospect even more likely.

Though the possibility of a contested convention is always a dream of political journalists and somehow never comes into fruition, there are two unique factors in this election cycle. One is the historic size of the Democratic field (creating more openings for more candidates to divvy up the delegates) and the other is the fact that the primaries and caucuses divide up their delegates on a proportional basis (unlike the crowded 2016 primary, in which Republican rules allowed Donald Trump to rapidly build up his delegate lead with victories in winner-take-all states).