Former state Sen. Jim Boyle of Gorham has declared his candidacy for governor in 2018, adding to a growing list of Democratic contenders.

Boyle made an announcement Tuesday morning but registered with the Maine Ethics Commission quietly a day earlier, joining five other Democrats.

“Maine was once a place where you could work hard and build a good life for your family. It didn’t matter if you lived in Fort Kent, Portland or Millinocket,” he said in a statement. “But those opportunities no longer exist for too many people. I can’t sit on my hands and watch Maine become a place where hard-working people get left behind.”

Boyle served one term in the Maine Senate from 2012-14 before narrowly losing to Republican Amy Volk of Scarborough, who was reelected in 2016.

The 58-year-old owns an environmental consulting firm. He is the latest name to enter a rapidly growing field of candidates seeking to succeed Gov. Paul LePage, whose second term ends.

Adam Cote was the first Democrat to declare back in April but he has been joined recently by Janet Mills, Maine’s attorney general, and Mark Eves, former speaker of the House.

Betsy Sweet and Patrick Eisenhart also have declared their candidacies.

The Republican slate of primary candidates is still thin, with only Mary Mayhew, former Department of Health and Human Services commissioner under LePage, entering the race to date.

This story will be updated