An Alaska judge refused on Thursday to block an investigation into whether Gov. Sarah Palin abused her power in firing her public safety commissioner.

Judge Peter Michalski threw out the lawsuit filed by five Republican state legislators. The lawsuit argued that the investigation had been tainted by partisan politics and was aimed at damaging Palin shortly before the Nov. 4 U.S. presidential election.

But the judge disagreed, saying, "It is legitimately within the scope of the legislature's investigatory power to inquire into the circumstances surrounding the termination [of] a public officer."

Palin fired the public safety commissioner Walt Monegan in July. He says he was fired for refusing to dismiss a state trooper who had gone through a nasty divorce with Palin's sister.

Monegan claims he was pressured by Palin, her husband and members of her staff to fire the trooper.

Governor denies accusation

Palin has denied the charge and says he was dismissed over budget disagreements.

The five Republican lawmakers had argued that the legislative body that ordered the investigation exceeded its authority. The judge's ruling was released just minutes before Palin and U.S. Sen. Joe Biden faced off in a debate in St. Louis.

Michalski agreed with defense attorney Peter Maassen, who argued that the Alaska legislature has the authority to investigate the governor as it sees fit.