WASHINGTON — Democratic Maine Senate hopeful Troy Jackson assaulted another man during a late-night rampage nearly four decades ago, a newly unearthed police report shows.

The March 12, 1988, brawl was apparently over Jackson’s longtime love Lana Pelletier, whom records indicate is also his second cousin and with whom the Democratic nominee shares two adult children.

The police report, first reported by the Bangor Daily News, indicates Pelletier told cops at the time that Jackson “pushed her around,” a statement she now denies making.

Jackson, then 19, had gone to a home in the town of Fort Kent, located on the Canadian border, at around 2 a.m. on the night in question, according to the report.

After the occupant of the house told Jackson to go away, the report says the future state lawmaker “kicked the door in” and grabbed his rival by the throat before punching him in the face, causing the victim’s glasses to leave a cut.

An enraged Jackson then told the unidentified man to “stay away from Lana Pelletier or else.” After the victim latched on to Jackson’s arm, a friend broke up the combatants.

The police report described Pelletier as Jackson’s ex-girlfriend, who claimed that he shoved her after the fight and that she intended to pursue a “cease harassment” order against him.

There is no indication that Pelletier ever sought the order and she has disavowed the police account of that night.

“I do not remember making the statements attributed to me, and they are not accurate. This is the first time I have seen this report from 40 years ago,” Pelletier told The Post in a statement.

“Troy and I have built a life and family together, and I know the person he has been through the decades since, both as a caring partner and father.”

The 1988 brawl is the only criminal case tied back to Jackson, and the court file has since been destroyed, according to the Bangor Daily News. However, there are indications that he paid $50 to resolve the issue.

“Nearly forty years ago, when I was 19 years old, I got into a fight with another man. I took responsibility for it then, and I take responsibility for it now,” Jackson told The Post in a statement.

“But let me be clear: I have never been violent with my partner Lana, or any other woman. This happened nearly four decades ago, and I assure Mainers this incident in no way reflects the man I am today or the life I’ve led in the years since.”

Jackson, 58, was nominated by Maine Democrats to face Sen. Susan Collins (R-Maine) last month after their initial nominee, Graham Platner, dropped out following rape accusations from a former girlfriend.

The Democrat has a reputation for having a hair-trigger temper and previously faced accusations that he chucked a water bottle at a female state Senate colleague during a fiery argument.

Jackson’s campaign acknowledged the dispute, but claimed he did not target the woman with the bottle.

A fifth-generation logger, Jackson spent a total of 20 years in the Maine Senate, the last six as president of the chamber.