ANCHORAGE, Alaska (CNN) -- Allies of Alaska Gov. Sarah Palin asked a judge Tuesday to halt the state Legislature's investigation into the firing of her public service commissioner, calling the probe a "McCarthyistic" inquisition.
Alaska state Sen. Hollis French is overseeing the investigation and is named in the lawsuit.
The five Republican state lawmakers who filed suit 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."
Palin, the Republican nominee for vice president, is battling allegations that she and her advisers pressured then-Public Safety Commissioner Walt Monegan to fire a state trooper going through a bitter custody dispute with Palin's sister -- and that Monegan was terminated when he refused. Palin says she fired Monegan over budget issues, and denies any wrongdoing.
One of those named in the lawsuit, Sen. Kim Elton, declined comment Tuesday.
Elton, the Democratic chairman of the bipartisan Legislative Council that commissioned the probe, and state Sen. Hollis French -- another Democrat and the lawmaker overseeing the investigation -- were named as defendants. So was Stephen Branchflower, the former Anchorage prosecutor hired to investigate Monegan's firing.
The lawsuit alleges that Elton, French and Branchflower "are conducting a McCarthyistic investigation in an unlawful, biased, partial and partisan political manner in order to impact the upcoming Alaska general and national presidential elections."
Palin originally pledged to cooperate with the investigation that the Alaska Legislative Council commissioned in July. But since becoming Sen. John McCain's running mate, campaign spokesmen have lashed out at the probe as "tainted" and "partisan," and fought to get the state Personnel Board to launch its own probe.
"I think it's fair to say that the governor is not going to cooperate with that investigation so long as it remained tainted and run by partisan individuals who have a predetermined conclusion," McCain-Palin campaign spokesman Ed O'Callaghan said Monday.
In particular, campaign officials singled out comments French made to ABC News that they said suggested the investigation could yield criminal charges or an "October Surprise" for the GOP ticket. And they accuse the probe of being "hijacked" by Democratic presidential candidate Barack Obama's campaign -- a charge the Obama campaign dismissed as "complete paranoia."
Monegan said he was repeatedly pressured to take action against State Trooper Mike Wooten, Palin's ex-brother-in-law, before his July dismissal.
Monday, the McCain-Palin campaign released documents it said bolster its argument that Monegan was fired over budget disputes and "egregious insubordination."