Cuf, the youth wing to the Centre Party which mixes an agrarian focus with a libertarian bent, took to Twitter on Tuesday:
"Two days left until Leftie Christmas Eve! If you see some zombie-like leftwing propaganda marches, take a picture and tag it with #thewalkingred"
Två dagar kvar till vänsterjulafton! Får ni syn på ett lite zombieaktigt vänsterpropagandatåg - ta en bild och tagga med #thewalkingred!— cuf (@cuf) April 29, 2014
But as several thousand Swedes prepare to take part in traditional workers' movement marches across Sweden, the allusion to the extremely violent US television series The Walking Dead has caused some upset. A chief complaint, however, was that Cuf has asked its supporters to register others' political beliefs (åsiktsregistrering), which is illegal in Sweden.
Cuf chairwoman Hanna Wagenius denied the accusation.
"It isn't about hanging May Day demonstrators out to dry, it's a political campaign," she said about Cuf's goal to talk about "dead politics that should not be brought back from the grave".
Cuf has accused the opposition Social Democrat party of "zombie politics", and argue that the left-of-centre party wants to backtrack several of the centre-right government's reforms if it gets into power after the September elections.
"A few people have taken offence and and feel we've encouraged violence or something similar," Wagenius told Aftonbladet. "That's not the case. We want to bring attention to the Social Democrats' zombie politics."
The joke was lost on lawyers Anela Rasic and Erik Mägi, however, who later on Wednesday reported Wagenius to the police for slander, incitement to commit crime, and breaking Sweden's personal information laws.
"We believe what she has done is criminal, and the risk is that people won't dare to demonstrate," Mägi told the Metro newspaper.
Mägi said he did not believe Wagenius had consciously broken the law, and isntead accused her of being naive.
"I don't think it was her intention to consciously subject people to threats," he said.
The original tweet caused a bit of a fracas on Twitter during the day. Swedish media strategist Brit Stakston called it provocative and "very liberal".
Hotel and Restaurant Union chairwoman Jenny Bengtsson, who is set to give a speech in Stockholm during the labour day parade, promised to photograph every Cuf member in return.
Folkbladet newspaper editor Fredrik Jansson tweeted that he didn't care about having his picture taken, but asked "are you going to photograph my children while you're at it?".
May Day is a public holiday in Sweden. The first Swedish labour day marches took place in 1890.