It’s every political reporter’s dream, but it has never happened in the modern age of primaries: a contested convention. That is, the Democratic National Convention in July may not be merely a pep rally and a coronation. The delegates may not simply be rubber stamps. They may be the people who get to pick the 2020 Democratic nominee.

If more than two candidates are winning delegates through March, it’s entirely possible that no candidate will get the 1,991 pledged delegates required to win on the first ballot in the convention. (There will be 3,979 pledged delegates, and 1,991 amounts to 50%+2 delegates, which is what the rules require.)