New Jersey Sen. Cory Booker’s campaign on Friday released a petition urging the Democratic National Committee to rethink debate qualification standards — the same day the New Jersey Democrat failed to meet the DNC quota.

A reported eight other 2020 candidates have acknowledged Booker’s concerns and signed his petition — including front-runner and former Vice President Joe Biden. In a joint statement, they allege that the DNC’s policy of barring certain candidates from the debate stage has “unnecessarily and artificially narrowed” what the group refers to as “the most diverse Democratic field in history,” according to the memo obtained by The Hill.

“The escalating thresholds over the past few months have unnecessarily and artificially narrowed what started as the strongest and most diverse Democratic field in history before voters have had a chance to be heard. As a result, candidates who have proven both their viability and their commitment to the Democratic Party are being prematurely cut out of the nominating contest before many voters have even tuned in — much less made their decision about whom to support,” the candidates allege.

Biden, South Bend Mayor Pete Buttigieg, former Housing and Urban Development Secretary Julian Castro, Andrew Yang, Tom Steyer, Minnesota Sen. Amy Klobuchar, Vermont Sen. Bernie Sanders and Massachusetts Sen. Elizabeth Warren have all thrown support behind the Booker petition, The Hill reports. (RELATED: Dems Speak Spanish Eight Times During First Segment Of Debate)

The Dec. 19 debate stage will only be occupied by candidates that were able to produce proof of at least 200,000 “unique contributors,” as well as at least four polls that place that candidate at a minimum of 4%. Two state-level polls at 6% would also suffice, according to Ballotpedia.

Booker stands at 2% on national average polls, but is not alone in the realm of dwindling support. Colorado Sen. Michael Bennet, former New York City Mayor Michael Bloomberg, Castro, former Maryland Rep. John Delaney, Hawaii Rep. Tulsi Gabbard, former Gov. of Massachusetts Deval Patrick, and Marianne Williamson have also not made the cut, NPR reports.