Mr Richards insisted that handing over to his deputy, David Davies, was merely a temporary measure while he fought the charges against him. A former Welsh Office minister, he is due in court in Richmond, south-west London, next month charged with grievous bodily harm against 22-year- old Cassandra Melvin on 27 July in Kew, west London.
It is claimed that Mr Richards, 52, grabbed the victim by the arm and pulled her around. Ms Melvin hit her elbow on a parked car and suffered a fracture.
Last night, a Tory party spokesman said: "It is my understanding that Rod Richards has stood down as leader of the Conservatives in the Welsh Assembly... [he] denies any wrongdoing but has stood down in the interests of the party pending the outcome of the proceedings against him."
Born in Llanelli and a Welsh speaker, Mr Richards is married with three children. He was educated at Llandovery College and University College, Swansea. He was elected to the Commons in 1992 but lost his Clwyd North West seat in the 1997 general election. He was forced to resign as a Welsh Office minister in 1996 when revelations about his private life appeared in a newspaper.
Mr Richards said last night: "I have asked David Davies, Tory business manager in the Assembly, to take over until this matter is sorted out. It is a temporary arrangement and I fully attend to take up the post of leader again once this matter is fully resolved." Speaking outside his home in Radyr, Cardiff, he said he had "no idea" why the allegations had been made against him and insisted he would "vigorously deny" the charges.
He said he had enjoyed an evening out at a pub in Richmond before going for a pizza with two sisters. He had never met the women before but they had agreed to accompany him for a meal if they could share a taxi home. He said he learnt of the allegations against him only this week, adding: "I went to the police station as I was required to do... I gave a true version of the events of that evening and I do not believe I can say much more at this stage."Reuse content