Jeremy Corbyn has signalled his determination to keep fighting the renewal of Trident by becoming a vice-president of CND.
The Labour leader is facing a major split in his party over whether Britain's nuclear deterrent should be replaced, with a crunch Commons vote due in the coming months.
Mr Corbyn was rebuked by colleagues last month for undermining the internal debate after bluntly stating that there were no circumstances under which he would authorise use of the weapons.
The veteran left-winger has been vice-chair of CND, which campaigns for unilateral disarmament by the UK, for many years. He had been due to address the organisation's conference in London this weekend, but he is now said to have other engagements.
CND said that while Mr Corbyn was stepping down as vice-chair in recognition of his increased workload, he would take on the role of vice-president instead. "He didn't want to resign from CND, so he decided to accept a vice president role," a spokesman said.
General secretary Kate Hudson said: "This is a fitting tribute to a very principled man with a lifelong commitment to CND and the cause of nuclear disarmament.
"Working together, with enormous support from across society, we will prevail against Trident and secure a crucial step towards global disarmament."