The first debate will be on two nights, 26 and 27 June 2019. Here is an article laying out all the details.
The First 2020 Democratic Debate Is Almost Here. Here’s Everything You Need to Know
There is a large field of candidates, requiring two groups. This is the group for the 26th
Elizabeth Warren
Beto O'Rourke
Cory Booker
Julián Castro
Tulsi Gabbard
Jay Inslee
Amy Klobuchar
Bill de Blasio
John Delaney
Tim Ryan
For the 27th
Joe Biden
Bernie Sanders
Pete Buttigieg
Kamala Harris
Kirsten Gillibrand
Michael Bennet
Marianne Williamson
Eric Swalwell
Andrew Yang
John Hickenlooper
Elizabeth Warren gets the soft draw. This may be good, because she can stand out, but she will not get to face her principal opposition.
Bernie, Biden, Buttigieg and Harris headline the second debate. This could cause fireworks. Harris desperately needs momentum. Buttigieg can show he belongs. Biden has chance to staunch the bleeding. Bernie has a stage and a podium.
This is just the first round. More is coming and the participation standards get tougher.