PORTLAND, Maine — Maine Democrats delivered a rebuke to their party’s system of superdelegates on Saturday by adopting a proposal at their state convention to reduce the clout of unpledged elected officials and party insiders.

The adopted proposal strips power from superdelegates by requiring the state party chairman to account for their preferences and ensure the delegation sent to the national convention reflects the outcome of the state vote.

But it doesn’t take effect until 2020 for fear of running afoul of national party rules and causing Maine’s delegation to be penalized.

The proposal’s sponsor was inundated with messages from Democrats in other states seeking to follow Maine’s lead.

‘‘That’s what happens when you have a good idea,’’ said state Rep. Diane Russell, of Portland. ‘‘It takes root, and it grows.’’

Maine will send 30 delegates, including 16 pledged delegates for Senator Bernie Sanders of Vermont and nine for Hillary Clinton, to the Democratic National Convention in Philadelphia. The delegation also includes five superdelegates, at least three of whom support Clinton.

The proposal allows the state party to work around national rules giving autonomy to superdelegates, who are unpledged elected officials and party insiders, to ensure state delegations to the 2020 national convention reflect the will of rank-and-file voters.

During debate Saturday, Brigham McNaughton, a Democrat from Freeport, received a rowdy ovation when he described a ‘‘rigged system’’ in which superdelegates are allowed to defy the will of the voters.

‘‘No one is super. We are all in this together,’’ added another speaker, Joanne Twomey, from Biddeford.