State Sen. Dan Wolf announced Thursday that he has suspended his campaign for governor and will resign his state Senate seat next week in the wake of a state ethics commission ruling about his ownership of Cape Air.

Mr. Wolf, a Democrat from Harwich who has represented the Cape and Islands since 2010, is also the founder and part-owner of Cape Air. In early August, the Massachusetts Ethics Commission ruled that because Cape Air has agreements with Massport to fly into and out of Logan Airport, Mr. Wolf was violating state ethics law. The commission said he must either end all leases and operating agreements between Cape Air and Massport, divest all his holdings in Cape Air, or resign his state Senate seat and end his gubernatorial campaign.

In a statement released early Thursday morning, Mr. Wolf said that he could not in good conscience pursue the first two options because cancelling the contracts would destroy Cape Air and divesting his holdings would “fundamentally undermine the company.”

“Without a change in the ethics commission’s position, I will resign my senate seat effective Thursday, August 29,” Mr. Wolf said in the statement. “I would do so under duress. I would do so believing that the Cape and Islands senatorial district is being denied duly elected representation.”

In July, Mr. Wolf announced that he was running for governor. In his statement Thursday, he said he is also suspending that campaign.

Mr. Wolf was elected to the state senate in 2010, and was re-elected without contest in 2012. He serves as chairman of the joint committee on labor and workforce development and vice chairman of the joint committee on state administration and regulatory oversight. He founded Cape Air in 1988, and the airline now flies to airports in 10 states and in the Caribbean.

The state ethics decision issued a formal advisory opinion to Mr. Wolf on August 2 stating that his 23 per cent ownership interest in Cape Air violated section seven of the state conflict of interest law. The commission said that Mr. Wolf sought the commission’s opinion in April because of his intention to run for governor.

An exemption to the state ethics law is possible if the contract is competitively bid and the legislator’s ownership interest, including the interests of his or her immediate family, is less than 10 per cent.

“While we understand that this situation creates difficult choices for Senator Wolf, there is no basis for the commission to give him special or different treatment,” commission executive director Karen L. Nober wrote in a state ethics commission statement released August 8.

Mr. Wolf said in his statement Thursday that he does not believe Cape Air’s agreements with Massport are state contracts that create a conflict of interest for him as a public official. “These are fixed fees and leases with identical terms and conditions for any airline that uses Logan,” he said. He said that Cape Air has used Logan for 25 years under agreements that are automatically renewed.

Mr. Wolf said the only appeals process available would be to take the matter to the superior court. “Spending a significant amount of money in the weeks and months ahead appealing a state ethics commission ruling is anathema to me. It is far from the kind of conversation I want to conduct, or our commonwealth deserves: How to make government work for working families and those in need and how to rebuild our middle class,” he said.

Brian McNiff, a spokesman for Secretary of State William Galvin’s office, said that if Mr. Wolf does resign, the state senate would have to adopt an order to hold a special election for the seat. A special election is not mandatory, he said, and if the senate does not vote to have an election, the seat would be left vacant until the end of Mr. Wolf’s term in 2014.

After Mr. Wolf announced his run for governor, state Rep. Sarah Peake, a Democrat from Provincetown, announced she would be running for his state senate seat.

Cape and Islands state Rep. Timothy Madden told the Gazette Thursday that Mr. Wolf’s resignation “would be unfortunate.”

“I think it was great that he was running [for governor],” Mr. Madden said. “I don’t really know what more you can say.”

He said he had hoped that Mr. Wolf and the state ethics commission would come to an agreement, and is still holding out hope for that outcome. He said he didn’t question the ethics commission, but does have a tough time seeing how they came to the conclusion they did.

“It seems unfortunate all the way around,” Mr. Madden said.

The complete text of Senator Wolf’s letter follows.

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In early August, the Massachusetts Ethics Commission ruled that I am in violation of state ethics laws because the company I founded 25 years ago, Cape Air, has agreements with MassPort to use Logan Airport, and I still have an ownership interest in the company.

Since then, I have been searching for a way to reconcile this decision with my own understanding of the situation, my responsibilities to the people who elected me as state senator from the Cape and Islands, my hope to become the next governor of the Commonwealth, and my respect for the principles of open and transparent government that created the commission in the first place.

I do not believe Cape Air’s agreements with MassPort are state contracts that create a conflict of interest for me as a public official. These are fixed fees and leases with identical terms and conditions for any airline that uses Logan. Federal regulations require that every qualified airline must be allowed to use the facility, so there is no opportunity for discretion, negotiation, or influence. Cape Air has used Logan for 25 years under such operating agreements that automatically renew. MassPort does not pay Cape Air; Cape Air leases space and pays a fee, like a turnpike toll or a charge for municipal water, to use a piece of public infrastructure.

The ethics commission has been aware since at least May, 2010 of my ownership interest in Cape Air. Not until August 2, 2013, three weeks after I announced my campaign for governor, did they rule that Cape Air’s use of Logan puts me in violation of ethics law. Their decision was made by the full commission without conversation or consultation with me leading up to the vote, no preliminary opinion and no opportunity for input. It was, as their own spokesperson put it, “written in the rush of things.” Nothing in their ruling in any way implies that I have acted or voted improperly as a state senator, only that Cape Air’s use of Logan violates the letter of the law.

The ethics commission offered me two options short of resigning from public office within 30 days:

• End all leases and operating agreements between Cape Air and MassPort.

• Divest all of my holdings from Cape Air, and end all associations with the company.

Ending all leases and operating agreements between Cape Air and MassPort would effectively prohibit Cape Air from serving Logan Airport, destroy a Massachusetts company, lead to the loss of 1,000 jobs, and end air service to 11 communities that rely on Cape Air as their sole year-round carrier.

That is not an option I can in good conscience pursue.

Divesting all of my holdings in Cape Air, and ending all associations with the company I founded 25 years ago, also would fundamentally undermine the company. Selling my shares to the company’s employees through the employee stock ownership plan created in 1996 would saddle them with serious debt as I walk out the door, and create significant cash flow challenges going forward. Selling my shares to a private owner would end employee control of the company’s future, removing protection from a forced merger or acquisition.

That also is not an option I can in good conscience pursue.

And so, without a change in the ethics commission’s position, I will resign my senate seat effective Thursday, August 29.

I would do so under duress. I would do so believing that the Cape and Islands senatorial district is being denied duly elected representation.

Until this matter is resolved, I am suspending my efforts to become the next governor of Massachusetts, believing that unless this ruling is changed I cannot conduct a campaign for real economic and social justice, defining a bright future for the commonwealth that includes affordable public education, a rebuilt infrastructure and healthy partnerships between the public and private sectors.

By statute, the only formal appeals process available for a full ethics commission ruling would be to take a case into superior court.

In a quarter century running an airline, I have never gone to court on a major matter, as either defendant or plaintiff. Spending a significant amount of money in the weeks and months ahead appealing a state ethics commission ruling is anathema to me. It is far from the kind of conversation I want to conduct, or our commonwealth deserves: How to make government work for working families and those in need and how to rebuild our middle class.

Unless the ethics commission reconsiders, taking both the spirit and letter of the law into account, acknowledging that the intent of the conflict of interest law was not to stop someone in my situation from serving the public, this will be my course of action.

At the founding of our nation, Thomas Jefferson talked about how successful citizens need to find time later in life to “put down the plow,” move into public service, contribute to a vital democracy, and then return to the field and private life.

That was my model when I first ran for office three years ago. But this ruling would force me to forsake and jeopardize the modern equivalent of my farm, a business built by many hands, and leave me nothing to return to after my time in public service.

Without a change of ruling, with deep regret, I will be submitting my resignation from the Massachusetts senate on August 29.