This is the list of people who are likely to announce a run. Assume these are your only options.

Apparently this is going to be a packed election because all of those people are considered to be very likely to run. If I included more likely to run than not I'd have to add 8 more. Maybe this is because the Democrats have extremely significant projected odds for winning the election for a forecast this early. So Democrats may do the Republican thing where every single Democrat runs.