Reform UK's Welsh leader, Dan Thomas, has resigned from his position following his arrest and subsequent release on suspicion of assault and controlling or coercive behaviour. Thomas was appointed as the Welsh leader of Reform UK by Nigel Farage in February and was elected as the leader of the opposition in the Welsh Senedd during the May elections. He announced his resignation on Tuesday, citing "personal reasons" and noting that he was reported to the police over the weekend and released without charge. Thomas maintained his innocence and said he did not want the incident to distract from the work of his party's Senedd team in holding the government accountable. According to Gwent Police, a 45-year-old man from the Aberbargoed area was arrested on suspicion of assault and controlling or coercive behaviour on September 13. He has been released on bail while further inquiries continue. Thomas previously served as a Conservative councillor in north London and is originally from Blackwood in Caerphilly. He became the first leader of Reform UK in Wales since Nathan Gill, who is currently in prison for accepting bribes in exchange for making pro-Russia statements in the European Parliament. In a separate development, Reform UK faced another challenge when Sarah Cooper-Lesadd, a member of the Senedd for Pen-y-Bont Bro Morgannwg, announced she was leaving Reform UK to join Plaid Cymru. She criticized Reform for not being serious about governing Wales, saying it was "far more interested in division, opposition and headlines than in finding solutions." Marc Jones, the Senedd group chair for Plaid Cymru, explained that Cooper-Lesadd's decision to defect followed discussions and reflection in line with the party's constitution. Thomas will continue to serve as a member of the Senedd representing Casnewydd Islwyn and stated he would support whoever the party selects as its next leader. He expressed regret over stepping down but noted the growth of Reform UK in Wales, which became the second-largest party in the Senedd after the May elections. Welsh Labour leader Ken Skates commented on the situation, criticizing Nigel Farage, Reform UK's leader, for demonstrating "appalling judgment."