AUGUSTA (AP) — A coalition that’s pushing for a referendum to set a state minimum for renewable energy fell short of the voters’ signatures needed by Monday’s deadline to force a November vote.

While Maine Citizens for Clean Energy missed the deadline to file the petitions with state election officials, the group promised to continue to gather signatures in hopes of sending a ballot initiative to voters next year. At least 57,277 voters’ signatures must be certified to put the proposal on the ballot.

Campaign officials did not say how many signatures they were short because they were still tallying those that had been collected, but they added they’re confident they’ll have enough for the 2013 vote.

“Going for the 2012 ballot was always a race against the clock. Despite the incredible enthusiasm from the public and from hundreds of campaign volunteers, the clock was just a little too fast for us to hit the deadline for the 2012 ballot,” said David Farmer, spokesman for Maine Citizens for Clean Energy. “One more week likely would have been enough. We’re that close.”

The referendum proposal would require that at least 20 percent of Maine’s electricity come from renewable energy sources, such as wind, tides and the sun, by 2020 and that utilities invest in energy efficiency whenever it would reduce energy costs for ratepayers.

The campaign had drawn opposition from Gov. Paul LePage, who promised to work for its defeat. LePage, a Republican, is taking his own proposals aimed at lowering energy costs to the Legislature and says that mandating certain forms of energy will not lead to lower costs.