TRENTON -- Writing to say he wants New Hampshire law enforcement to know "exactly what kind of governor Chris Christie has been back home in New Jersey," New Jersey State Policemen's Benevolent Association President Patrick Colligan on Tuesday sent an open poison-pen letter to officers in the early voting state.

Christie, a Republican presidential candidate who in December referred to Colligan last year as a "pension pig," has made securing the endorsements of New Hampshire's sheriffs and police chiefs a top priority for his campaign but struggled to win more of them.

In an interview with NJ Advance Media on Tuesday, Colligan fired back, saying he hoped to convince New Hampshire's law enforcement officers that the governor was "as far away from being a law enforcement candidate as you can get."

In his association's open letter to New Hampshire police and uniformed officers, the 24-year veteran of the Franklin Township police accused Christie of actually committing, not preventing, crime.

The governor "diverted our increased pension contributions to offset other spending in the state budget. He called it 'property tax relief,'" Colligan wrote. "As you know, when one person takes money promised by law for one reason and uses it for something completely different, we call it fraud."

Colligan said Tuesday that "the combination of increased pension and health care contributions have literally had us in a reverse slide in pay back to 2006."

His letter to law enforcement in New Hampshire, where many experts say Christie's White House bid hinges, is designed to prevent any further endorsements of the governor. In July 2015, Christie secured the support of Sheriff Scott Hilliard of Merrimack, the state's third-most populous county, but he has struggled to gain any further sheriff endorsements in the crowded field.

Colligan acknowledged that many in his group had actually backed Christie when he first ran for governor in 2009, but he is now determined to prevent New Hampshire police officers from doing the same.

"If he's going to walk around this country and say he still enjoys the support of law enforcement," Colligan said, "then I invite anybody from anywhere else in the country to call a New Jersey police officer and ask them what they think of Gov. Chris Christie."

Claude Brodesser-Akner may be reached at cbrodesser@njadvancemedia.com. Follow him on Twitter @ClaudeBrodesser. Find NJ.com Politics on Facebook.