A Liberal MP has threatened to pursue senior party figures, including three former premiers, in a battle with a former opposition leader over a mammoth legal bill.

John Pesutto, Victoria’s former opposition leader, was ordered to pay more than $2.3 million in costs to Liberal colleague Moira Deeming earlier in May, on top of $315,000 in damages.

It followed the Federal Court finding he defamed Deeming by implying she was associated with neo-Nazis who gatecrashed a controversial Melbourne rally she attended in 2023.

Deeming was expelled from the Liberal party room but welcomed back after winning the high-stakes trial. Pesutto was ousted as leader.

Since the costs order, Deeming’s legal team has written to Pesutto’s lawyers seeking information on some of his high-profile donors.

Her solicitor Patrick George indicated she will seek to recover costs from third parties and apply for subpoenas to compel Pesutto to disclose communications with his contributors.

Deeming said the legal letter, obtained by AAP, sought to understand who aided Pesutto’s legal defence as she may “have to seek cost recovery through them”.

“Being a lawyer, John knew better than anyone, the legal and financial risks in refusing to apologise and retract his defamatory claims against me,” Deeming said.

“His defences failed, I won my case and he agreed to pay my costs last year. Time has progressed but he still has 21 days from Friday to pay.

“He also still enjoys the ongoing public support of at least three powerful multimillionaire backers who can easily afford to pay it.”

Former Victorian Liberal premiers Ted Baillieu, Jeff Kennett and Denis Napthine were among Pesutto’s declared donors.

Pesutto declined to comment on the legal letter but said he appreciated their support.

He suggested the money his donors had contributed was “relatively modest” and conceded he wasn’t sure any would come to his aid again.

“I’ve got a challenge that I’m trying to meet,” he said.

“I want to do everything that I possibly can to raise the money that I owe Mrs Deeming.”

A GoFundMe campaign for Pesutto’s cause has raised just under $185,000.

He will be forced out of parliament if he declares bankruptcy, triggering a byelection in his marginal seat of Hawthorn, in Melbourne’s east.

Shadow attorney-general Michael O’Brien, another former opposition leader, described the legal letter as “bizarre” and “not helpful”.

Opposition Leader Brad Battin agreed it was a distraction for the party and wants the matter resolved.

“It is frustrating because it’s not a topic that I think most Victorians at home want us talking about,” he told ABC Radio Melbourne.

Battin turned heads internally in April when he made Deeming his “representative to the western suburbs”.

-AAP