Hillary Clinton Hillary Diane Rodham ClintonButtigieg stands in as Pence for Harris's debate practice Senate GOP sees early Supreme Court vote as political booster shot Poll: 51 percent of voters want to abolish the electoral college MORE skipped the MoveOn.org candidate forum, opting against answering questions from members of one of the nation's largest progressive groups.

Clinton, the Democratic front-runner, was not among the candidates taking questions in a video of the event released with little fanfare on Tuesday, as first reported by MSNBC.

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Sen. Bernie Sanders Bernie SandersButtigieg stands in as Pence for Harris's debate practice Bernie Sanders warns of 'nightmare scenario' if Trump refuses election results Harris joins women's voter mobilization event also featuring Pelosi, Gloria Steinem, Jane Fonda MORE (I-Vt.) and former Gov. Martin O'Malley (D-Md.), the other two remaining Democratic presidential candidates, took part in the forum.

Anna Galland, the executive director of the group's non-profit wing, warned that the decision could hurt Clinton's ability to motivate progressives.

"It’s a shame that Secretary Clinton declined to participate in the MoveOn member forum; she missed an opportunity to speak directly to and energize the progressive base she’ll need in her corner not just to win the nomination but also the general election, if she is the party's nominee," she said in a statement.

"Our forum gave grassroots progressives the chance to pose substantive questions directly to presidential candidates—exactly what democracy is about—and we’re grateful to Sen. Sanders and Gov. O’Malley for participating."

The Democratic National Committee (DNC) blessed the candidate forum in October in response to creeping criticism from O'Malley and other Democrats over the limited number of Democratic debates.

The party's first debate in October was the only one of the first three scheduled to take place during a weekday primetime slot, when viewership is higher.

November's debate fell on a Saturday night, earning only about half the audience of the first debate. A December debate is scheduled for the Sunday before Christmas.

Clinton signaled openness to more debates in September, vowing she would "show up anywhere the Democratic National Committee tells us to show up."

The MoveOn forum different from the debates in that the candidates did not respond to each other it was not sponsored by the DNC.

But Rep. Debbie Wasserman Schultz (Fla.), chairwoman of the DNC, praised the forum it in October as an "important" opportunity for voters to engage with the candidates.