Gov. Charlie Baker’s administration is facing a new investigation into explosive claims that GOP operatives at a patronage-laden state agency harassed and retaliated against a staffer after her fiance launched a campaign to unseat a Republican state senator, the Herald has learned.

The staffer claims she was first warned by a Baker loyalist currently at the Office of Energy and Environmental Affairs that she would face retribution if her fiance, J.D. Parker-O’Grady, went ahead with plans to run against incumbent state Sen. Donald Humason Jr., (R-Westfield).

The day after Parker-O’Grady launched his campaign, the staffer, Cynthia Lewis, who worked for the chief of the state environmental police, former Baker campaign driver Col. James McGinn, was told she was being transferred to a registration outpost in Fall River, according to a letter from Lewis’ lawyers.

“They told her if I were to hand in my signatures they would make her life miserable. And they did,” Parker-O’Grady told the Herald in a brief interview.

Lewis, a former staffer for GOP state Sen. Bruce Tarr, declined comment when contacted by the Herald.

But according to a “cease and desist” demand letter sent by her former attorneys to the EEA’s legal counsel, and obtained by the Herald, she was “subject to harassment, threats, coercion and intimidation” by Baker appointees in an attempt to get Parker-O’Grady to call off his Democratic challenge to Humason.

The letter says “within an hour” after Parker-O’Grady announced his campaign on Facebook, Lewis was contacted by EEA “personnel officer” Jared Valanzola, a failed GOP legislative candidate whose cousin Michael Valanzola, another failed GOP candidate, was appointed by Baker as chief operating officer at the agency.

“Jared informed Ms. Lewis that (Michael) Valanzola was disgusted with her, suggested she break off her engagement with Mr. Parker-O’Grady, and ominously stated that if Mr. Parker-O’Grady cared about Ms. Lewis’s career he would not turn in the nomination papers,” the letter states.

“Jared specifically told Ms. Lewis that ‘the Administration’ was unhappy and that if Mr. Parker-O’Grady continued his run, her career with the state would be over …”

Sources tell the Herald that the letter and allegations have prompted an internal investigation at EEA. Lewis’ legal team has also requested internal emails and warned the administration not to destroy any communications.

A spokesman for the Energy and Environmental Affairs, which is headed by former Republican state lawmaker Matthew Beaton, said “transfers are routine” but declined to comment on the allegations.

“While we don’t discuss personnel matters, anytime complaints are brought to our attention we take them seriously,” spokesman Peter Lorenz said.

The Herald has reported that at least a dozen administrators and staffers at the EEA, which oversees the Department of Conservation and Recreation, have ties to Baker’s campaign or are active in the state Republican Party.

They include McGinn, a former state trooper who the Herald reported landed his $134,000 job and a promotion to colonel after working as Baker’s driver during the 2014 campaign.

Baker is also facing fallout over a party top DCR administrators threw for Republican-connected staffers and guests at the July 3 Boston Pops rehearsal. Two top DCR administrators were suspended after admitting to using taxpayer-funded golf carts and other resources to hold the gathering that began at the Beacon Hill home of prominent Republican Ron Kaufman.

The new allegations and investigation swirling around Lewis’ proposed transfer could further tarnish the image of Baker, who campaigned as a reformer and fiscal conservative.

The complaint from Lewis’ lawyers says she was interviewed by Valanzola, who directly asked if she was “a registered Republican.” Lewis isn’t, but was offered the job after he noticed she worked for Tarr.

After Lewis was informed of the transfer, she resisted and later EEA officials offered to reimburse her $800 to take a bus to Fall River, according to her lawyers.

She continues to work out of McGinn’s Boston office while the investigation is ongoing.