The suspect who attacked MP Ben Zyskowicz (NCP) in eastern Helsinki on Saturday has been interrogated by Helsinki police.
According to Detective Inspector Kari Martikainen, who is leading the investigation, the suspect has been formally placed under arrest.
The 38-year-old man is suspected of assault and making unlawful threats.
Zyskowicz, who is Finland's longest-serving MP and the former longtime leader of the NCP parliamentary group, was knocked to the ground while on the campaign trail in Itäkeskus shortly before noon on Saturday. He suffered cuts and abrasions on his hands and knees.
Zyskowicz said the man insulted him over his Judaism and support for Nato membership. Zyskowicz's father was a Polish Jew who survived two Nazi concentration camps.
Under Finnish law, a criminal suspect must be either arrested or released within 24 hours of being taken into custody. Police had earlier said that the suspect would likely be released on Sunday.
A decision to remand the suspect must be made no later than noon on the third day after the arrest, i.e., next Tuesday.
According to Martikainen, the Helsinki police have not made any particular changes to their operations during the election campaign period as a result of Saturday's incident. During the last parliamentary election campaign period, four years ago, at least two candidates facing physical confrontations while on the stump.
"The police will continue to maintain public order. Of course, every candidate has campaign spots in various parts of the city, so it's hard to be everywhere, but we try to be visible as much as possible. There is no need for any stepped-up measures," said Martikainen.
Police declined to release any further details about the suspect or his possible motive, citing the ongoing investigation.