Federal MP and State Chairman for right-wing Alternative for Germany (AfD), Frank Magnitz, was assaulted by at least three men in Bremen as he was leaving a New Year’s reception party on Monday afternoon.
The police are investigating the case as a "politically-motivated act" and "suspected dangerous assault."
AfD has been the main opposition party in Germany since 2017.
The men, described by local police as wearing hoods and dark clothes, knocked the 66-year-old unconscious on the street close to the northwestern German city's Goetheplatz. Passing construction workers spotted him and called an ambulance.
Police analysing surveillance footage of the incident showing the suspects approaching Magnitz from behind. One of the unidentified individuals then hit Magnitz, whereupon he fell down and the three suspects fled.
While the police statement said the object used to hit Magnitz could not be determined from the CCTV footage, the AfD maintain he was hit with a piece of wood.
The party also claimed the 66-year-old was further kicked in the head while on the floor, however, the police statement makes no mention of this happening in the CCTV evidence.
A graphic picture of Magnitz injured in the hospital was posted to the AfD's local Facebook page, claiming that "not only the left but also the SPD and the Greens support antifascist groups and their attacks".
"The motive behind this is, above all, the everyday incitement against the AfD, for which the media and politicians of the old parties are responsible," AfD leader Alice Weidel added in a Facebook live video. The sentiment was echoed in a statement by party co-leaders Alexander Gauland and Joerg Meuthen.
Several relevant figures in the German political landscape condemned the attack.
German Chancellor Angela Merkel's spokesman, Steffen Seibert, wrote on Twitter that the "brutal attack" was "to be strongly condemned".
"Hopefully the police will succeed in catching the perpetrators quickly," he wrote.
Ex-Green Party co-leader Cem Özdemir took to Twitter, writing: "There is no justification whatsoever for violence against the AfD. Whoever fights hate with hate always lets hate win in the end."
The Free Democratic Party's National Chairman Christian Lindner said: "No matter how much I reject what the AfD stands for, violence is not a means of political strife."
SPD General Secretary Lars Klingbeil also condemned the act, writing: "Violence has no place in the political debate. Violence is cowardly."
European right-wing politicians have wished Magnitz a speedy recovery — French Rassemblement National spokesperson Jerome Riviere called the attack "an assassination attempt", while Dutch populist Geert Wilders voiced his full solidarity with the AfD.