Mrs Palin denies that she abused her position to settle a personal feud
A group of Alaskan state employees have agreed to testify at a probe into alleged abuses of power by Republican vice-presidential nominee, Sarah Palin.
Mrs Palin, who is governor of Alaska, denies claims she acted improperly in firing a senior state official.
The seven officials had previously refused to testify to the Alaska Legislative Council.
The news comes after a weekend of fierce campaigning between the Obama and McCain camps.
Alaska's attorney general said the seven public employees had agreed to give evidence to the Alaska Legislative Council about the affair which has become known as "Troopergate".
Mrs Palin is accused of removing Alaska Public Safety Commissioner Walt Monegan from his post after he had refused her request to fire her ex-brother-in-law, Mike Wooten, as a state trooper.
The investigation centres on the dismissal of Alaska's public safety chief
Mr Wooten was involved in a contentious divorce and child custody battle with her younger sister.
Critics say Mrs Palin was using her power as governor to pursue a personal feud.
But Mrs Palin insists that she fired Mr Monegan over disagreements about budget priorities.
An independent investigator, Steve Branchflower, is due to present his findings on 10 October.
Last Friday, an Alaskan judge rejected a lawsuit filed by Republican lawmakers which claimed the council had exceeded its authority when it ordered the probe.
Judge Peter Michalski said it was "legitimately within the scope of the legislature's investigatory power to inquire into the circumstances surrounding the termination [of] a public officer".
Republican politicians also claim the investigation, which began before Mrs Palin was named as running mate for presidential nominee John McCain, has become tainted by partisan politics.
A lawyer for the five legislators who brought the lawsuit claimed the timing and manner of the inquiry "violates the fundamental, affirmative individual constitutional right to fair and just treatment".
Mrs Palin's husband, Todd Palin, had previously refused to testify under subpoena to the investigator, although he was not a plaintiff in the lawsuit.
Both sides are campaigning hard as the race enters the final month
It is not known whether he or Mrs Palin will now testify in the case, which analysts say could damage the final weeks of campaigning for Mr McCain.
The development comes after Mrs Palin sparked controversy during weekend campaign stops when she claimed Democratic rival Barack Obama had links with terrorists.
She said he had been "palling around" with an ex-member of US-based militant group Weather Underground.
The radical movement waged a violent campaign against the Vietnam War during the 1960s when Senator Obama was a child.
Mr Obama once served on a charity board with a former member of the group, Bill Ayers, but he has denied any close links with him and has denounced Weather Underground.
The Illinois senator rejected Mrs Palin's accusations as "smears" and said Republicans were attempting to distract voters from the real issues.
The Obama campaign responded with a new advertisement, which will air nationally on cable TV stations, claiming Mr McCain has behaved erratically during the Wall Street meltdown and was "out of touch" on the economy.