Social Democrats TD Daniel Ennis is suing an online campaigner he claims attempted to smear him in advance of the Dublin Central byelection in May.Ennis, who won the Dáil seat, initiated High Court proceedings against Nick Delehanty on Wednesday. He is being represented by Terence F Casey and Co Solicitors.In a letter sent to Delehanty in May, Ennis’s solicitor Dan O’Connor accused the activist of sharing a “string of malicious and grossly defamatory posts” on X (formerly Twitter) that month.“You have directly sought to damage our client’s reputation through baseless innuendo of wrongdoing,” the solicitor wrote.Delehanty has denied defaming Ennis. The May letter included details of a number of posts Delehanty shared on X related to Ennis.Some of the posts sought to link Ennis with an individual who Delehanty claimed acts as a director of several companies providing accommodation to asylum seekers. Another post claimed Ennis was “at fault” for not disclosing his position as secretary of a company when elected as a Dublin city councillor in June 2024. This assertion was a “falsehood” as Ennis was not required to do so, the letter said.O’Connor said Delehanty’s posts suggested Ennis behaved unethically, which he described as a “slur” and “false and untrue and clearly defamatory”.The letter said the posts were “clearly designed to cause maximum reputational damage” in the lead-up to the byelection on May 22nd.O’Connor said Ennis was requesting “a full and unequivocal apology” and “written undertakings that the allegations will not be repeated”. The letter concluded: “If you do not agree to the above, our instructions are to issue High Court proceedings against you for defamation and necessary Injunctive reliefs without further notice or correspondence and we shall use this correspondence to ground our application for the costs of same.”Delehanty on Thursday said he “was not expecting proceedings to issue” and was taking legal advice.“I deny defaming Mr Ennis and will be defending the proceedings,” he said in a statement.“My commentary concerned public records, company filings and matters of public interest relating to a candidate for elected office.”The Irish Times has contacted Ennis and the Social Democrats for comment.Ennis became the party’s 12th TD in May, securing the seat vacated by former minister for finance Paschal Donohoe.Before entering politics, Ennis was best known for his football career, during which he played for League of Ireland sides Bohemians, Shelbourne and Bray Wanderers.Delehanty, a critic of multiculturalism, unsuccessfully tried to get on the ballot for last year’s presidential election and has previously run in local and general elections. He is a former solicitor and currently runs a day care service for dogs.