United Future's Peter Dunne yesterday expressed regret at remarks he aimed at two senior public officials over the election spending row.
Mr Dunne in August told the Herald that the former Solicitor-General, Terence Arnold, had delivered a legal opinion "in splendid isolation ... then skived off to the Court of Appeal".
The MP accused Auditor-General Kevin Brady of besmirching the reputations of politicians.
But yesterday Mr Dunne expressed regret over his remarks.
"I have fallen into the trap of allowing my strong personal views that their inquiries have been characterised by naivete and a lack of natural justice to cloud my public judgment and reaction," he said.
"I now regret that very much."
He said those office holders "for the time being are entitled to public respect, whatever one's view of their individual actions in particular cases".
United Future says that if it is directed to do so, it will try to pay back taxpayers' money unlawfully spent last election, but it won't necessarily pay it all back if it is not directed to do so.
Mr Dunne said that by his party's own assessment, it had breached the rules to the tune of $4965.30 and would pay that to the Parliamentary Service no matter what Mr Brady said in his final report.
But that amount falls well short of the $40,000 thought to have been identified in the draft report as unlawful expenditure by United Future MPs.
The Progressives were found not to have unlawfully spent anything, National and the Maori Party have already repaid their amounts, the Green Party and Act will pay, and New Zealand First said that it would, but only if a good case was made for doing so. Labour Minister Pete Hodgson has said the party won't pay but Prime Minister Helen Clark has not confirmed that as Labour's position.