With a large and growing field of presidential wannabes to juggle, the Democrats are changing the way they select who takes part in their pre-campaign debates.

In the past, declared candidates were assigned debate slots based on polling. Those with the most support according to pollsters were assigned to one debate, those trailing, to another.

Democratic National Committee Chairman Tom Perez tells the Associated Press he plans to add “a grassroots fundraising metric” to polling as a way to make choosing debate participants more inclusive.

The Democrats’ first two debates will take place in June and July, with four more to come this year and “at least six more to follow in 2020.”

Perez says he’ll announce details by the end of this week, which will include an element of chance — drawing lots — to the process of assigning candidates to one or the other of the first two debates.

In an analysis of the current state of the Democratic field, the Washington Post’s Philip Bump set up a tongue-in-cheek “horse race” involving 10 declared or potential candidates. Instead of polls, he used numbers from PredictIt — a “prediction market” that lets users bet on the outcome of any event — converting dollars wagered to percentage points.

The outcome: Sen. Kamala Harris (D-CA) leads the field with 22% support, while Sen. Kirsten Gillibrand (D-NY) and former New York City Mayor Michael Bloomberg trail, with 5% each.