Suffolk County Legislator Al Krupski said this week that he will run for Southold Town supervisor in the November election.

Mr. Krupski (D-Peconic) has long been whispered as a public figure destined for the top job in Town Hall, and he made it official this week. His announcement comes in the final year of Supervisor Scott Russell’s term in office. Mr. Russell, who has served as supervisor since 2005, has said for months he would not run for reelection.

Over Mr. Krupski’s years in public office, he has been one of the strongest voices for preservation of open space — particularly farmland — and has been a strong advocate for the health and well-being of the Peconic Bay estuary.

“I live in this town and I think it’s a great place to live,” Mr. Krupski said in an interview Monday. “I’m very familiar with its workings and its people, and I want to keep it that way, so it will be the same for my grandchildren.”

Mr. Krupski has been a Suffolk County Legislator representing the North Fork since 2013, when he overwhelmingly defeated then-Riverhead Town Supervisor Sean Walter in a special election to fill a vacant seat, winning 67% of the vote. In terms of his winning elections, Mr. Krupski has been one of the biggest Democratic vote getters in the county.

Mr. Krupski has had a long career in public service, all of which pointed to an eventual run for town supervisor. He served as a Southold Town councilman for seven years and a town Trustee for 20 years. All along, he has kept his family’s farm in Peconic going. The Krupskis have been farming on that rich soil for four generations.

“We’ve kept the farm going, but we have considerably cut back the operation,” he said. ”As a public servant, I can’t dedicate the time to it that I did decades ago.”

Mr. Krupski said he screened before the Southold Democratic committee a couple of weeks ago. It’s been common knowledge in town politics that Mr. Krupski would not run for supervisor if Mr. Russell stayed on the job. In an interview, Mr. Krupski praised Mr. Russell for his service to Southold.

“Scott did a very good job,” Mr. Krupski said. “He was a dedicated public servant and he was great to work with. And I worked with him for a long time.”

He praised his decade on the County Legislature, saying, “It was a great experience to serve on the County Legislature. I worked with a lot of great people there. It’s a great diverse county and I liked the experience. I’ve just been really blessed to represent great communities all these years — with Southold, all of Riverhead and eastern Brookhaven — they are really great people.”

Asked if there are any specific projects he wants to work on should he be elected supervisor, he said, “I’ve always run on my environmental record. Land preservation and water quality are really the main driving issues. And obviously, traffic is always a big concern.”

Asked to comment on Mr. Krupski’s candidacy, Mr. Russell joked: “I figured he was [running] when he started stenciling his name over my sign in my parking space. Seriously, when he wins, the people of Southold will be electing the best supervisor this town has ever had. Serving as supervisor for Southold is the greatest honor someone can be given. I can’t think of anyone who deserves that honor more than Albert.”

Peter McGreevy, the chair of the Southold Republican committee, said, “Albert is the most conservative Democrat you will meet, and rumors of his running (for supervisor) were circulating for well over a year. As Scott Russell’s final four-year term ends, and Albert’s term limits in the county Legislature approach in two years, this is his opportunity to step back in to Southold politics.”

Kathryn Casey Quigley, chair of the Southold Democratic Committee, said, “I’m thrilled that he screened and the Democratic screening committee does intend to nominate him. He’s a phenomenal elected official who’s very passionate about this town and the community, and we’re excited about his bid.”

She said the screening committee has finished interviewing candidates and the overall committee will nominate its candidates on March 2.