AUGUSTA — The Maine ethics commission says the state must close a campaign finance loophole that allowed a publicly funded Democratic candidate to ask his volunteers to pay for $1,800 worth of mailings.

Commissioners want to clarify the so-called house party exemption, a rule meant to allow volunteers to pick up part of the costs of campaign events – up to $250 per election.

“This is a huge loophole that could potentially result in thousands of dollars of private money in what is supposed to be a clean election process,” Commissioner Richard Nass said.

The Maine Commission on Governmental Ethics and Election Practices this week voted 3-2 against further investigating Rep. Ben Chipman, who won a Democratic state Senate primary in Portland. The commission had previously unanimously voted not to continue investigating Chipman during its May meeting, and at Wednesday’s meeting discussed reopening the matter.

Chipman had 10 volunteers pay a Portland mail house for a $1,828 mailing that highlighted two house party events.

Commissioner Meri Lowry noted that they could again consider reopening the investigation, if they receive new evidence.

The May 18 ethics complaint was formally launched by Portland resident Steven Biel, who supported Chipman’s primary opponent Democratic Rep. Diane Russell of Portland.

Though some commissioners had more criticism for Chipman’s actions than others, all expressed concern that Chipman complied with the statute, but went beyond its intent.

Chipman had sought and received advice from the ethics commission staff regarding the mailings, which he said complied with state campaign finance law because the individuals were going to volunteer at the house parties.

Jonathan Wayne, the commission’s executive director, said Chipman didn’t mention the cost or number of invitations.

Commissioners want to prevent exploitation by prohibiting volunteers from sharing the cost of campaign event invitations. The proposed rules would only allow the one volunteer who provides property for the event to pay for such invitations.

A public hearing on the proposed rules is scheduled for Aug. 10. Commissioners may vote on the rules on Aug. 31.