A sex video has ended French ruling party candidate Benjamin Griveaux's hopes of becoming mayor of Paris, reports BBC News.
The ex-spokesman for President Emmanuel Macron's government, who was already trailing in the race, was apparently targeted by a Russian protest artist accusing him of hypocrisy.
"No-one should be subjected to such abuse," said Mr Griveaux.
The video, showing a man in a compromising position, quickly spread on social media late on Thursday.
Petr Pavlensky, who sought asylum from Russia in 2017, said he had posted the video online.
Opponents from across France's political spectrum voiced their outrage.
Incumbent Mayor Anne Hidalgo appealed for respect for people's private lives, while far-left leader Jean-Luc Mélenchon condemned the attack as "odious". Prime Minister Edouard Philippe expressed his support for his former colleague.
The video appeared on a little known website that featured a profile of Mr Griveaux's political ambitions and his "fanatical faith in family values". It then alleged that Mr Griveaux had exchanged intimate mobile phone messages with a young woman and sent her a personal video.
A link to the site was shared by an MP who was forced to resign from Mr Macron's LREM (Republic on the Move) party in late 2018.
Mr Griveaux told the BFMTV news channel that for the past year he and his family had been subjected to "defamatory remarks, lies, rumours, anonymous attacks... and even death threats".
"This torrent of mud has affected me and above all hurt the people I love."
Mr Griveaux's lawyer said he would press charges over the publication of the video, which he said violated the right to a private life.