AUGUSTA, Maine — Members of the Maine Ethics Commission on Wednesday unanimously ruled that a Republican senator from Bangor didn’t improperly coordinate with a political action committee to funnel $73,000 into advertising targeting her opponent.

The commission ordered no further investigation into allegations raised by the Maine Democratic Party. The party pointed out in a formal complaint with the ethics commission in early October that Farnham was listed as a principal officer and decision maker for the Senate Republican Majority PAC when the committee purchased $73,000 in television advertising targeting her opponent, Democrat Geoffrey Gratwick.

The commission, however, did find the PAC at fault for failing to update its registration paperwork when the principal officers changed. The five-member commission assessed a $250 penalty, citing a Maine law that requires political committees to update their registration documents within 10 days of changing officers.

Democratic Party lawyer Kate Knox said the party didn’t accept Farnham’s explanation that she volunteered her name as a “placeholder” principal officer last winter at a time when both of the PAC’s principal officers — Senate Republican Majority Leader Jon Courtney and Assistant Republican Leader Debra Plowman — had resigned to pursue federal office.

“You are either in or you’re out, and candidate Farnham’s listing on the PAC registration form meant she’s in,” Knox said. “I know of no other corporation or organizational structure where principal officers are allowed to assert they’re not responsible depending on what the situation is.”

But Farnham, fellow Republican Sen. Tom Saviello of Wilton, and a Republican Party lawyer told ethics commission members Wednesday that the Bangor senator had no involvement with PAC fundraising or decision-making, and that her name should have been removed from the PAC’s registration paperwork months ago.

“I told them at the very beginning I would be a placeholder,” Farnham said. “I know that it was important to be done. It was not important to me. I said, ‘Put my name on here so I could be a placeholder for this PAC. I won’t be involved.’”

“It is unfortunate that my name wasn’t taken off there” when the committee found new officers, she said.

Much of the discussion before the ethics commission focused on whether the presence of Farnham’s name on a political action committee’s registration documents automatically indicated that she coordinated with the committee to spend money on her race.

Despite the commission’s finding that there was no coordination, “I don’t fault the complainant for bringing it up,” said commission Chairman Walter McKee.

It is illegal for candidates to coordinate with outside organizations that are spending money on their races. If coordination happens, it’s considered a contribution to the candidate. And in Farnham’s case, she can’t accept any contributions because she’s receiving public campaign financing under the Maine Clean Election Act.

The ethics commission also discussed whether a political committee should list officers who are considered “placeholders” and don’t intend to be involved in committee affairs.

“It is not good enough to, in retrospect, say you were a placeholder and define that term completely outside of the statute,” said Knox, the Democrats’ lawyer. “Candidate Farnham told us she was a decision maker [through the registration documents], and it is solid evidence that she played a significant role in the PAC’s affairs.”

But Republican Party lawyer William Logan said Maine law requires that coordination actually take place.

“There is no ‘per se’ coordination that says, ‘If you’re the principal of a PAC, then the PAC can’t spend money on you,’” he said. “It is theoretically possible to create a firewall. Perhaps it’s not advisable, but there is no per se coordination in the statute or in regulations.”

Since they filed the complaint at the beginning of October, Democrats and affiliated groups have made the ethics allegations against Farnham a political rallying point, calling attention to them recently at a rally in Bangor and in a series of anti-Farnham radio and TV ads sponsored by the Committee to Rebuild Maine’s Middle Class, a political committee backed by Democratic-leaning groups.

The Senate District 32 race between Farnham and Gratwick has attracted more spending from outside groups than any other state legislative contest this election cycle. As of late Wednesday, outside groups supporting Farnham or Gratwick had spent $414,000 on the race.

The Maine Ethics Commission on Wednesday also took up two other complaints involving the Farnham-Gratwick race: one that Democrats filed against Farnham alleging she was late in reporting an expenditure for video production, and another that Republicans filed against Gratwick alleging some of his campaign mail lacked a required funding disclosure statement.

In both cases, the ethics commission found the candidates in violation of the law, but did not assess any penalties.