The campaign to bring a privately run casino to Oxford County was dealt a blow Tuesday when Pat LaMarche said she would no longer serve as the effort’s spokesperson.

LaMarche, a well-known Maine political figure and former Green Party candidate for governor and vice president, said her resignation is effective immediately.

“I’ve promised the people of Maine I would never lie to them and if I keep this job, I would have to break that promise,” LaMarche said.

Maine voters will decide at the polls in November whether the state should allow a casino at an undisclosed location in Oxford County.

LaMarche said she still believes a privately run casino would be good for western Maine’s tourism economy, but staying with Evergreen Mountain Enterprises, the corporation set up to run the campaign, would go against her ethical standards, she said. She declined to elaborate.

The company was created by Seth Carey, a Rumford lawyer, who also wrote the referendum language. Carey recently made headlines as the subject of a review by the Maine Board of Overseers of the Bar, the panel that provides oversight for lawyers. Carey is facing possible sanctions for a series of complaints filed by fellow lawyers and two judges.

LaMarche issued a one-page news release announcing her resignation on Tuesday morning.

“It is with a heavy heart that I turn my back on what I truly believed to be a remarkable opportunity for Oxford County in particular and Maine in general,” LaMarche wrote in the prepared statement. “I can’t remember the last time that I quit something. I’m just not a quitter.”

LaMarche joined the campaign in April. She said negotiations with private investors, who were looking into buying Evergreen, broke down recently and that she couldn’t continue without new owners for the corporation, which would ultimately run the casino if approved by voters.

LaMarche said that at the time she was hired, Carey did not disclose to her his pending trouble with the state’s Board of Overseers of the Bar or an assault charge filed against him, which was eventually dropped.

“I was supposed to represent the project, not be a shield behind which they would hide moral failings and disreputable conduct,” she said.

Carey, who could not be reached for comment earlier in the day, issued a statement via e-mail Tuesday evening, expressing disappointment in LaMarche’s decision to leave the campaign.

He wrote that the corporation disputed there were any “legal or professional issues that would in any way hinder the project” and hinted that LaMarche had quit for financial reasons.

The campaign has been operating without paid staff while trying to secure funding from an investor who shares the corporators’ vision, Carey wrote.

“We will continue to pursue funding and once successful we hope we are able to re-engage Pat in her role as spokesperson,” he wrote.