AUGUSTA — Dozens of activists called on legislators Tuesday to make Maine the latest state to formally endorse a U.S. Constitutional amendment that they say would keep special interests from having an excessive impact on elections.

The rally at the State House, led by Maine Citizens for Clean Elections, closely followed the third anniversary of the U.S. Supreme Court’s Citizens United decision, which stripped away many campaign spending restrictions that had applied to corporations and unions.

“We need a U.S. Constitutional amendment that will allow us to regulate the raising and spending of campaign funds on a federal and state level,” said Andrew Bossie, executive director of the clean elections group, to cheering participants at the rally. “We also need to clarify the nature of corporate entities in their roles in our elections and governments.”

Bossie’s group is also concerned that Gov. Paul LePage’s proposed budget would cut $4 million from the state fund that covers campaign expenses for eligible legislative and gubernatorial candidates, which would essentially eliminate the program in the 2014 elections.

Bossie said that comes at a time when the state needs to be strengthening its Clean Election Act, “not weakening it.”

With the Citizens United decision, independent and third-party organizations were allowed to contribute as much as they wanted to influence races in Maine’s 2012 legislative elections.

That’s what happened in Democratic Sen. Geoffrey Gratwick’s campaign, in which he unseated Republican Sen. Nicki Farnham of Bangor in November. Each candidate was allocated $21,000 for the campaign under the Clean Election law, while outside parties spent $450,000 on the race.

“This is not just wrong, this is obscenely wrong, this is outrageously wrong,” Gratwick said at the rally. “This is not money given by local citizens, this is not money given by local businesses. This is money given by people with a different agenda than those I represent in Bangor and Hermon.”

The advocates displayed a stack of more than 11,000 postcards from voters calling on lawmakers to support the constitutional amendment.

Several legislators and some local officials attended the event.

Bossie said Maine would be the 12th state to formally offer support of a constitutional amendment, should it pass in the Legislature.

At least 25 Maine towns have passed resolutions calling for a constitutional amendment, and several more are considering it, Bossie said.