Democracy for America and the PCCC said they will no longer back his Senate run.
The roundtable had been rescheduled after the Dallas shooting earlier this month.
The creator of the group that performed at a Trump rally now plans to sue the campaign.
"I'm hoping that somebody comes here and arrests you," Rep. Alan Grayson told a Politico reporter.
That position would put Clinton in line with Donald Trump.
The former DNC chair "had become a flashpoint," said John Podesta.
Watch the live stream from the second night of the Democratic National Convention.
Recently elected Rep. Warren Davidson now has no Democratic opponent.
Moishe Mana's effort is only the latest to pressure Trump into releasing his returns.