The next Democratic presidential debate will be in Westerville, Ohio (near Columbus) on Tuesday, October 15. It will have 12 candidates on the same stage. They include the ten who debated in September, and Tulsi Gabbard and Tom Steyer.
This is probably the largest number of presidential candidates on the same stage ever sponsored by a U.S. major political party. In 2015 Republicans held an eleven-candidate presidential debate on September 16 in Simi Valley. There was also a lesser debate for a few candidates who had not qualified for the main debate.