Todd Palin is refusing to testify in an abuse-of-power investigation targeting his wife, the Republican vice-presidential nominee Sarah Palin.

Mr Palin had been subpoenaed to appear before Alaska lawmakers today in the potentially explosive “Troopergate” probe, which is examining allegations that as governor his wife improperly dismissed a cabinet member because he refused to fire her former brother-in-law.

But although the Palins initially pledged to co-operate with the inquiry, they have changed tack since the governor’s selection as John McCain’s running mate and are now claiming a political motivation to the case.

In a letter to Stephen Branchflower, the independent investigator, yesterday, the Palin family lawyer Thomas van Flein described the investigation as politically biased and lacking legal authority.

“We maintain our general objections that the legislative council investigation, besides being pursued for partisan purposes, is being conducted in violation of all accepted norms of due process,” Mr van Flein wrote.

Though bipartisan, the probe is being overseen by the head of the Alaska state Senate judiciary committee, who is a Democrat.

The subpoena rejection throws into question whether the probe’s final report, due October 10, could now be completed before Americans go to the polls on November 4.

Todd Palin, who has five children with the Republican governor, was among 13 people ordered to testify in the Troopergate probe, which centres on the dismissal of Walter Monegan as the Alaskan public safety commissioner.

Mr Monegan claims that he was fired by Mrs Palin because he refused to dismiss a state trooper, Mike Wooten, who had gone through a bitter divorce with Mrs Palin’s sister. Mrs Palin maintains that she fired the commissioner because of policy differences and rejects his claim that she improperly pressured him to fire Mr Wooten, against whom she had made complaints before her election as governor.

Mr Van Flein also argued that the subpoena was “unduly burdensome” because of Todd Palin’s travel schedule. Mr Palin is campaigning with his wife in US battleground states ahead of the election.

“Because his spouse is her party’s nominee for vice-president of the United States, his scheduling obligations over the next two months will make it virtually impossible for him to prepare for and present the testimony called for in the subpoena at the specified location during that time period,” Mr van Flein wrote in the letter, reproduced on the Alaska Daily News website.

State lawmakers voted last week to allow the independent investigator to issue subpoenas after witnesses refused to be interviewed for the investigation.

Mrs Palin was not subpoenaed, but her husband and several members of her staff were.

The governor initially welcomed the investigation, telling an Alaskan news channel just last month: “I want them to ask me these questions, I don’t have anything to hide and didn’t do anything wrong there.” But she later acknowledged that pressure on Mr Monegan “could have been perceived to exist, although I have only now become aware of it”.

Since she joined the Republican ticket, the McCain campaign has been working hard to shut down the probe, appointing Ed O’ Callaghan, the former chief of the US attorney’s terrorism and national security unit to develop its legal strategy.

Yesterday, Mr O’ Callaghan said Thursday that the Palins no longer believed the Legislature’s investigation to be legitimate.

Legal experts say the stonewalling of witnesses is likely to stall the probe until after the election.

Democratic state senator Kim Elton said yesterday that the committee which approved the investigation may be reconvened to consider a postponement or the replacement of Democratic state senator Hollis French as its manager.

The Legislative Council, made up of 10 Republicans and four Democrats, had unanimously approved launching the probe. But since Mrs Palin’s nomination, some Republican members of the committee have requested a review, claiming the affair has become overly politicised.

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