MONTPELIER, Vt. — A Vermont environmentalist who leads a group pushing for the cleanup of Lake Champlain says he’s going to challenge Republican Gov. Phil Scott in next year’s election as a Democrat.

James Ehlers filed his candidacy with the Vermont Secretary of State’s office on Thursday. Ehlers is the first candidate to announce he’s running for governor in 2018.

Ehlers is the executive director of Lake Champlain International, which advocates for cleaner water and runs fishing competitions on the lake.

Ehlers has called for greater public investment in government programs. He’s also been critical of the Scott administration for not doing more to pay for cleaning up Lake Champlain.

Scott, at his weekly news conference Thursday, said he would seek re-election next year, but he was not ready to announce his candidacy.