FOX6 News asked the Republican National Committee on Sunday how many candidates will actually take the stage, and a spokesman said he didn't want to "get ahead" of the debate.
"We expect to have a lot of great candidates there, a lot of candidates that have a great story to tell and really, a record of success to share with American voters," said RNC Strategic Communications Director Tommy Pigott.
Prep for Republican presidential debate at Fiserv Forum
So far, 10 Republicans have said they qualify to take part on the first debate – including Florida Gov. Ron DeSantis and former Vice President Mike Pence. Asa Hutchinson, the former governor of Arkansas, said he is qualified and coming, too.
"We're excited for our candidates to really take the stage for the first time and give that alternative to Joe Biden," Pigott said.
Former New Jersey Gov. Chris Christie said Trump should come to Milwaukee: "Nobody ran against him in 2020. Why are all these people running now? I mean, he needs to answer those questions, and he owes it to the voters to do it."
The deadline to qualify for the debate is 48 hours from the event's start, which means 8 p.m. Monday night. More details are expected after that deadline.
Trump had been discussing a number of debate counterprogramming options, including sitting for an interview with ex-Fox News host Tucker Carlson, who has been hosting a show on X, the website formerly known as Twitter.
The Associated Press contributed to this report.