AUGUSTA — A Republican state senator said Tuesday she will resign after a special legislative panel found that some ballots cast for her had been double counted and that the Democrat had really won the tight Cumberland County race.

Democrat Cathy Breen will now take the District 25 seat ”“ pending final approval by the state Senate ”“ ending a weeks-long dispute in the Statehouse that caused tension among lawmakers as they opened a new legislative session.

Cathy Manchester, who had been provisionally seated by the Republican-led Senate last week, said she intends to submit her letter of resignation and thanked the committee for getting to the bottom of the matter.

“I am disappointed with the outcome but I have full confidence that senator elect-Breen will serve our district well,” said Manchester, a former police chief from Gray.

Unofficial results on Election Night had shown that Breen won, but a recount a few days later flipped the race for Manchester.

However, 21 ballots found that were cast for Manchester in Long Island didn’t match the number of people that the town clerk had said voted on Election Day, spurring questions among Democrats about possible ballot tampering.

After the ballots were examined again Tuesday, Deputy Secretary of State Julie Flynn said it appeared that those 21 ballots were accidentally counted twice for Manchester during the recount. When the committee ordered the ballots to be counted again, it found that Breen had actually won the small island community by 30 votes ”“ matching the results on Election Night.

Breen said she was thankful for voters’ patience during this “confusing” time.

“It’s been a bumpy ride, but I really appreciate everybody who has kept informed and kept in touch, and I’m happy to say it has come to a conclusion that I was hoping it would,” said Breen, a former Falmouth town councilor.

The mystery over the Senate seat has dominated the beginning of the 127th Legislature, which was sworn in last week but doesn’t begin its real work until January. Despite Breen’s win, Republicans will still control the Senate, holding 20 seats compared to Democrats’ 15.

Members on the committee suggested that legislative changes may be needed to improve the election and recount process to prevent such a mistake from happening again.

But lawmakers, election officials and the candidates all expressed relief that it appeared to be human error, and not something more sinister.

“I don’t like that it was our error, but I do like that it was an error and not fraud,” Flynn said.

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