Adrienne Esposito, Executive Director of Citizens Campaign for the Environment,...

Adrienne Esposito, Executive Director of Citizens Campaign for the Environment, speaks during a press conference at Farmingdale State College on Sept. 04, 2012. Credit: Newsday / Amanda Voisard

For a decade, Adrienne Esposito has been a top Long Island environmentalist, known to the powerful locally and in Albany as she fought for everything from installing sewers and protecting groundwater to halting a liquefied natural gas terminal in the Sound.

But Esposito, executive director of the nonprofit Citizens Campaign for the Environment, says she is now mulling a run for State Senate on the Democratic line, even though she is a nonaligned voter.

"I've had discussions," she said. Esposito said that while she has been approached about running in the past, she is taking a serious look because "an open Senate seat has tremendous power over the issues I care about."

The 3rd District seat, which GOP state Sen. Lee Zeldin of Shirley is vacating to run for Congress, is one of three on Long Island that could be crucial to Democrats for tipping control from a coalition of State Senate Republicans and several dissident Democrats.

Esposito, 53, of Patchogue, has met twice with Suffolk Democratic chairman Richard Schaffer and also with state Sen. Michael Gianaris, of Queens, head of the Senate Democrats' campaign committee, and will sit down with Gianaris again this week. She said she expects to decide in the next 2 1/2 weeks.

"I think she wants to take it to the next level," Schaffer said. "She's more than qualified to be senator."

Assemb. Steven Englebright (D-Setauket) said he has encouraged Esposito to run. "She would bring all her skill to bear if elected and would soon emerge as one of the most important voices for Long Island's environment and coastal New York. We need her."

Esposito's name has taken center stage because Patchogue Mayor Paul Pontieri, who had been the leading Democratic contender, appears to be backing off the race, associates say.

"I haven't decided about running and they haven't decided on me," Pontieri said.

Some Esposito allies say they do not want to lose her as a front-line advocate.

"Long Island would be losing a real champion . . . she accomplishes so much through her advocacy," said Richard Amper, executive director of the Long Island Pine Barrens Society. "I think she can do much more from the outside than she could ever do inside the government."

Esposito has never run for public office, and would have to amass a multimillion-dollar campaign war chest and branch out into issues including education, taxes and social services. There also is the question of how much support she could get from Schaffer, who says privately he sees a GOP-controlled Senate as better for suburban interests.

John Jay LaValle, Suffolk GOP chairman, warned that Esposito's candidacy would change how she and her organization are viewed.

"She's done a good job as an environmental advocate," LaValle said. "But once you run for office, it removes your credentials as a nonpartisan person for the rest of your life." Should she lose, he said, "You can't show up two weeks later and say you're representing the environment."

The GOP has a half-dozen contenders for the seat, including town board members Anthony Senft of Islip and Tim Mazzei of Brookhaven.

Senft also has crucial Conservative Party backing.

Also unclear is what would happen to the Farmingdale-based Citizen's Campaign, which Esposito has built over 29 years into a group with five offices around the state and one in Connecticut.

Esposito emphasized she has made no decision.

"There a lot to think about," she said. "I love what I do now and it would be hard for me to give it up."