Italy’s already dramatic electoral politics got a jolt of the unexpected this week when a far-right candidate who aspires to become the Italian Republic’s first female leader, Giorgia Meloni, posted a pixelized video to social media that purported to show a woman being raped by an asylum-seeker in the northern city of Piacenza. Her decision to do so has fired up opponents and sent the Italian media into a tailspin.

Ms. Meloni, the leader of the Brothers of Italy party, which has neo-fascist roots, on Sunday evening reposted a video on Twitter from an Italian news site that was taken by a witness from a window overlooking a street in the Italian city of Piacenza, south of Milan. The woman, identified as Ukrainian, can be heard yelling in distress. A 27-year-old asylum-seeker from Guinea has been arrested in the sexual assault, according to Italian media reports. 

On Tuesday, Twitter removed the video and an Italian newspaper, La Stampa, reported that Facebook and Instagram removed it as well, but the sparks are still flying.

“One cannot remain silent front of this atrocious episode of sexual violence in broad daylight in Piacenza by an asylum-seeker,’’ Ms. Meloni wrote prior to video’s removal. “A hug for this woman. I will do everything possible to restore security to our cities.”

Her main opponent in the September 25 vote, Enrico Letta, the Democratic Party leader, countered in a radio interview that reposting the video went beyond “the bounds of dignity and decency.”

A former education minister, Lucia Azzolina, said posting the alleged rape video “is not an official criminal complaint, but instrumentalization’’ of violence. She said seeing “a woman, candidate to run the country, using this media, is chilling.”

The leader of a new centrist party called Action, Carlo Calenda, said Ms. Meloni “has done something not worthy of a civilized country, and against women.”

Ms. Meloni’s allusion to security in Italian cities is a right-wing theme in this election campaign, which also hits at immigration. She was backed by a coalition partner, Matteo Salvini, the leader of the right-wing League party and former firebrand interior minister, who pledged that “defending our borders and Italians will be a duty for me, not a right.”

In a video response to Mr. Letta’s criticism, Ms. Meloni emphasized that no one is identifiable in the video and that the center-left leader had failed to condemn the attack itself.

“Why don’t you speak of this? Because otherwise you need to come to terms with the fact that security in our cities is out of control, thanks also to the surreal immigration policies that you have pursued,’’ Ms. Meloni said.

Polls show the Brothers of Italia having a potential lead with voters over the Democratic Party in the approach to the parliamentary election, but neither have enough support to govern alone.

Ms. Meloni can expect a significant boost from her coalition partners — the League and Silvio Berlusconi’s center-right Forza Italia party — while Mr. Letta is aligned with much smaller parties.

The timing of the video controversy is not ideal for the rising star of Rome. As Italians gradually return to the cities after their August holidays, her every move will come under much greater scrutiny, especially with the election just more than a month away.