PHILADELPHIA — As Democratic presidential candidates scramble to meet requirements to participate in the next round of debates, Tom Steyer can’t even get on the stage at a liberal conference.

Steyer, a billionaire investor, was originally slated to appear at the keynote address Thursday at the annual Netroots Nation conference but was removed from the lineup after he announced his candidacy Tuesday.

Mary Rickles Conley, the communications and political director for Netroots Nation, told the Washington Examiner that Steyer was booted “for equity’s sake.”

“The only opportunity for candidates to speak was the forum,” she said in an email, referring to a presidential candidate forum scheduled for Saturday.

But Steyer did not meet the criteria to be able to appear alongside his 2020 rivals. Conley said the threshold was determined by polls from the liberal activist website Daily Kos.

It was not immediately clear what the polling threshold was.

Alberto Lammers, a spokesman for Steyer’s campaign blamed the lack of appearance on a scheduling conflict, saying the candidate had been asked to appear on Saturday's panel but he "was already committed to doing events in South Carolina."

Sen. Elizabeth Warren, Sen. Kirsten Gillibrand, former Housing and Urban Development Secretary Julian Castro and Washington Governor Jay Inslee are among the candidates expected to appear on Saturday’s panel at Netroots, an annual conference for left-wing activists and politicos.

The move comes as several candidates jockey to be included in the next round of Democratic National Committee-sponsored debates, which will happen in Detroit on July 30 and 31.