Former Portsmouth Mayor Steve Marchand is running for governor, the third Democrat to enter the race.
He announced his campaign via Facebook.
He tells Seacoast Online that combating the state's heroin and opioid crisis will be his top priority.
"The explosion in deaths, in overdoses, in pain to thousands of homes across the state remarkable," he told the paper in announcing his plan to run.
Marchand served as Portsmouth's mayor from 2005 to 2008. He also worked as director of corporate relations for the University of New Hampshire.
He's expected to hold a news conference Thursday morning in Manchester to formally announce his candidacy.
Executive Councilor Colin Van Ostern and Mark Connolly, the state's former top securities regulator, are also running for the Democratic party's nomination in the race to replace outgoing Gov. Maggie Hassan, who is running for U.S. Senate.