Police said they believe a 43-year-man driving a white Toyota Landcruiser struck Ms Haines outside her office on Murphy Street about 3.35pm.

"When he exited the Toyota the driver, a 43-year-old Tarrawingee man, was arrested at the scene by a passerby," Victoria Police said.

"The woman was taken to hospital with critical injuries."

Police said a knife was located by officers and seized from inside the Toyota.

Are you fucking serious? So angry at a politician that you try to kill her? She isn't even a member of a political party - so you can't pin it on overall anger at Labor/Libs for something or other.