David Seymour reckons women's rights advocate Kate Sheppard and Māori chiefs who signed the Treaty of Waitangi would have voted for ACT.
It comes after he claimed Nelson Mandela would have also thrown his support behind ACT if the South African leader was still alive.
Seymour told attendees of a Business NZ conference in Wellington on Tuesday that he believed Sheppard, who founded the women's suffrage movement, would have given ACT her vote.
"I have read some of Kate Sheppard's quotes and she believed in universal human rights, she opposed racial discrimination, I suspect that she would be voting for us today," Seymour said.
He went on to say that Sheppard may have actually voted for the Greens as she was in favour of the "prohibition of alcohol". Green MP Julie Anne Genter, who was appearing alongside Seymour on a panel, looked confused.
Former Prime Minister Helen Clark tweeted her shock: "What next!"
"This week the claim is about Kate Sheppard, leader of #NZ #women's suffrage movement. Election campaigns are often referred to as silly seasons; QED."
Later in the day when speaking about the Treaty, Seymour said: "I believe many of those chiefs, if they were around today, would be voting ACT."
"ACT has quite a number of supporters. I have to say, we are mostly going for the living voters, not exclusively."
Seymour has made that claim before.
"Limited government, self-determination, property rights and equality. I reckon the chiefs who signed the Treaty would sign up to ACT today," he said in February.
Last month, when giving a public speech, Seymour said Mandela would have campaigned for ACT. But Mandela's grandson ridiculed this.
"My grandfather definitely loved the people of New Zealand and I can say categorically he would not campaign for this today or any other day in the past," he wrote.