ANCHORAGE, Alaska (CNN) -- What was once an ugly divorce involving Gov. Sarah Palin's sister is now at the center of a political showdown in Alaska and on the campaign trail.
The question: Did Palin, her husband, Todd, or any of her staff put pressure on the state's top cop to fire the governor's ex-brother-in-law, State Trooper Mike Wooten?
An investigator hired by Alaska lawmakers plans to subpoena Palin's husband and several of her staff.
"He's made many comments about how it appeared that DPS [the Department of Public Safety] is not doing its job because of Wooten. He wanted him fired, and I'm hoping that the subpoena, if issued, will permit me to interview him," said investigator Stephen Branchflower.
Now, Republican lawmakers in Alaska argue the investigation has become a political circus. They call it partisan payback. It's already a distraction, if not yet an embarrassment, for the governor. Five state lawmakers have sued to block the investigation.
They said the two Democrats and the former Anchorage prosecutor leading the probe "are unable to hold the balance between vindicating their own political interests and the interests of those who are being investigated." Watch as the Palin probe turns political »
Sen. John McCain's campaign said it's being driven by two prominent supporters of Sen. Barack Obama.
On Monday, the McCain-Palin campaign announced that Palin will not cooperate with a "tainted" legislative investigation.
Former Palin Press Secretary Meg Stapleton told reporters in Anchorage that the investigation has been "hijacked" by "Obama operatives" for the Democratic presidential nominee -- namely, Alaska state Sen. Hollis French, the Democratic lawmaker managing the investigation and an Obama supporter. French has denied working on behalf of the Obama campaign.
The Obama campaign described Stapleton's charge as "complete paranoia." It has denied sending campaign staff to Alaska to work with the legislative committee's investigation.
So how did the investigation get here?
Claims by Palin and her family that three years ago in the middle of the divorce, Trooper Wooten repeatedly threatened them -- even allegedly threatened to kill her father.
Wooten denies that. Palin conceded her staff expressed concern about Wooten to Walt Monegan, the top cop.
"The state trooper has threatened, you know, to kill my dad," Palin has said.
But she insists as governor she did not pressure anyone to fire Wooten. She told ABC last week her husband had met Monegan but did not pressure him to fire Wooten.
"He did, very appropriately though, bring up those concerns about a trooper who is making threats against the first family and that is appropriate," she said.
Now, the McCain campaign says, Palin "did not learn of these contacts by Todd Palin, until August of this year" even though Todd Palin met Monegan in her office soon after she became governor. Monegan insists he was fired in July because he didn't sack the trooper, though he says he wasn't told directly to fire him.
"I believe I was fired because I did not fire Mike Wooten," Monegan has said.
The McCain campaign is now providing dozens of e-mails that it says show Monegan lost his job for "egregious insubordination."
"This final straw came in late June and early July of this year when Commissioner Monegan arranged for yet another unauthorized trip to Washington, D.C. to request more financial assistance from Congress," said Palin campaign spokeswoman Meghan Stapleton.
Still, even some Republicans in Alaska say Monegan's firing was badly handled and hurt Palin's credibility. They include a former U.S. attorney who was an informal ethics adviser to the governor.
In a letter dated July 24, Welby Shay told Palin he had "grave concern" about the "naive, unprofessional" counsel she'd received in the Monegan case. He declined to speak on camera but told CNN, "If they would have done what I said, I think it would have been over."
A spokeswoman for the governor said that "while we can't always act on every idea, Gov. Palin thanks Mr. Shay for his counsel."
CNN political producer Ed Hornick contributed to this report.