The 60-year-old was left with multiple facial fractures and bleeding on the brain after the alleged attack outside his home on Scorpio Street in Torquay, southwest of Geelong, at about 7.45pm on Sunday.
The man had confronted two people who were damaging One Nation signs on his property, the party reported on Tuesday.
Police responded and arrested two people - a 14-year-old boy from the Casey area and a 37-year-old man from Hampton Park.
The older man was charged with intentionally causing injury and other assault-related offences and remanded in custody to appear at Geelong Magistrates' Court on November 10.
The 14-year-old was issued with a caution.
The alleged victim was taken to hospital with non-life-threatening injuries, with his work vehicle also allegedly badly damaged in the attack.
Senator Hanson said she wouldn't speculate as to whether the attack was specifically politically motivated.
The One Nation leader, who was in nearby Geelong to assist with campaigning for the upcoming Victorian state election, said she had spoken to the man personally and seen his injuries.
An image shared online by Senator Hanson showed the man's badly bruised, swollen and still-bleeding face.
"He heard some ruckus on the property and then he went to investigate and apparently they were destroying the signs," Senator Hanson said.
"He asked them... 'what are you doing?'.
"And they actually ran for him and then viciously attacked him.
"The reasons behind this attack I just don't get it, I don't understand."
As of Tuesday afternoon a GoFundMe for the man had raised more than $117,000.
One Nation Victoria leader Warren Pickering described the alleged attack as "un-Australian".
"I understand this is a critical election without recent precedents. I understand many Victorians are frustrated. I understand the temperature of debate is high," he said.
"We don't have to accept the erosion of the middle ground for respectful debate or peaceful disagreement.
"We must build that ground up and give it unassailable foundations."
Premier Ben Carroll said the incident was shocking and called for a "civil, peaceful" election.
"Whether you're wearing a red, a blue, an orange, or a green T-shirt, they are volunteers," he said.
"They are out there doing what they believe is right, and no one should be coming under attack."
Every Victorian has the right to express their political views and support the party of their choice without fear of violence or intimidation, Liberal leader Jess Wilson said.
"We can disagree strongly about politics, but violence is never the answer," she said.
The attack cast a troubling shadow over the official start of the Victorian state election period on Tuesday, with the signing of writs by Governor Margaret Gardner.
The writs will be delivered to the electoral commissioner, formally dissolving the state's 60th parliament and officially setting a date for the election as November 28.
Victorians still have until 8pm on Tuesday to make sure they're enrolled.
Victorian Electoral Commissioner Sven Bluemmel said he had been in contact with police to discuss measures to protect staff, volunteers and the public on voting day.
Political corflutes are heavily limited within 100 metres of voting booths and for the first time field compliance officers will monitor behaviour at various election hubs.
"Beyond that, our remit is actually quite limited," Mr Bluemmel said.
"It's an important thing also to remember that in the vast majority of cases, people show up, they might have different views on policies, but they ... cast their ballot and have a sausage and have a good day.
"We want as much of that as possible."
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