Independent member for Indi Helen Haines remains in a critical condition after being hit by a large SUV outside her electorate office in Wangaratta, northern Victoria, on Monday afternoon.
Dr Haines, 65, was reportedly retrieving something from the boot of her car when the Toyota Landcruiser allegedly made a U-turn, hit her, reversed and hit her again, according to eyewitness accounts relayed by government ministers.
She was airlifted to a Melbourne hospital and remains in critical condition after undergoing surgery overnight.
A 43-year-old man from the nearby town of Tarrawingee was arrested at the scene and could be charged with causing harm to a Commonwealth public official, according to the Australian Federal Police.
If found guilty, he could face a maximum of 10 years' imprisonment.
While Victorian counter-terrorism authorities join the AFP and spy agency ASIO in the investigation, federal police Commissioner Krissy Barrett said there was no ongoing threat to the community.
"At this stage it appears this is an isolated incident, and there are no known threats connected to this matter," she said in a statement on Tuesday.
"The AFP provides regularly briefings to parliamentarians about their safety and security, and further briefings will be undertaken soon."
The statement came minutes after Ms Barrett, along with Victorian Police Commissioner Mike Bush, briefed Home Affairs Minister Tony Burke and Prime Minister Anthony Albanese.
Ms Barrett said federal police had repeatedly warned the public about growing threats against political figures.
There were 1067 reports of harassment and offensive or threatening behaviour against high office-holders, federal parliamentarians, electorate offices and protected establishments in 2025 and 2026, she said.
A task force established in October 2025 to disrupt high-impact, politically motivated violence and similar potential crimes has also charged 41 people for threatening federal politicians and political higher-ups, the commissioner added.
Whether the attack was politically motivated is expected to form the basis of the investigation, Victoria Police Acting Superintendent Ashley Mason said earlier on Tuesday.
He added there was no recent evidence the suspect was on authorities' radar before the attack.
Major crimes officers from Melbourne have travelled to Wangaratta while the suspect was held in custody overnight.
It is unclear whether the man was known to Dr Haines.
"This wasn't something with a car just going off the off the road, this is something that is very clear was aimed at causing harm to Helen Haines," the prime minister told News24 earlier on Tuesday.
But the incident was an example of a "permissive environment of violence", according to Australia's top spy Mike Burgess, who on Tuesday joined pleas to turn down the temperature of political discourse.
"This incident occurred in an environment where politically motivated violence is more likely than previous years," the ASIO director-general said in a statement.
The security environment was heading in a concerning direction despite the terror threat remaining "probable", he added, meaning there is a greater than 50 per cent chance of an onshore attack or planning in the next year.
Mr Burgess said making debate in Australia more civil was imperative.
The attack has sent shock waves across the political spectrum, prompting calls to firm up politicians' security and outpourings of adoration from all quarters for the well-liked and respected MP.