The University of Southern California canceled a gubernatorial debate planned for Tuesday after candidates of color said the university used discriminatory standards to decide who would participate, The Associated Press reported. USC’s Dornsife Center for the Political Future and KABC-TV had planned the forum as part of a crowded campaign for California governor.

According to the AP, USC’s original participant list included Republican Steve Hilton and Republican Chad Bianco, and Democratic candidates Tom Steyer, Katie Porter, Eric Swalwell and Matt Mahan. The AP said those candidates met the criteria used to select the debate’s participants.

The AP reported that four established Democratic candidates of color—Antonio Villaraigosa, Xavier Becerra, Betty Yee and Tony Thurmond—were excluded because they did not meet the formula’s requirements. The exclusion triggered accusations from the candidates of color and others that the approach discriminated against them.

USC initially defended the selection formula and denied bias allegations, the AP said. The university said in a statement that a public policy professor independently developed the criteria based on candidates’ polling and fundraising, and the AP reported that the criteria had been independently supported by a group of policy and social science scholars.

A group of 50 scholars from across the country defended the professor in a letter to USC’s president on Monday, the AP reported. In the AP account, the signatories urged USC to reject “political pressure” on its faculty and academic mission.

Despite that defense, USC reversed course Monday night, according to the AP. The university said the debate co-hosts could not agree on a solution, and it described the controversy as a significant distraction from the issues voters care about.

The AP also connected the dispute to broader pressure within the Democratic Party ahead of California’s June 2 primary. It said state Democratic Party Chair Rusty Hicks urged candidates to drop out if their campaigns were no longer viable, citing the possibility that two leading Republicans could advance to the general election under California’s top-two system.

The AP reported that Hicks publicized poll results commissioned by the party showing Hilton, Porter, Bianco, Swalwell and Steyer in close competition, with other candidates trailing. In the AP account, Hicks said the results confirmed the possibility of Democrats being locked out of the general election and added that candidates must honestly assess their path to win.

Much of the criticism, the AP said, focused on Matt Mahan’s inclusion over other candidates. The AP reported that Mahan, the San Jose mayor, joined the race later than some competitors but raised more funds, aided in part by contributions from ultrawealthy donors in Silicon Valley.

In an interview, Mahan told the AP he was disappointed the debate was canceled and said the other established candidates should have been allowed to participate. The AP also reported that Villaraigosa, who is Latino and a former Los Angeles mayor, celebrated the decision to cancel, calling it the right call even if it came late and under pressure.

Legislative leaders, including chairs of the Black and Latino caucuses, increased pressure Monday by calling for organizers to open the debate to more candidates, the AP reported. In the AP account, they threatened a boycott if USC did not give voters a fair shot at evaluating everyone running for governor.