British Prime Minister Tony Blair is to lay out plans Monday for a new multibillion pound nuclear deterrent, a move expected to be among his last major acts as prime minister - and one likely to cause friction in his governing Labour party. Blair's Downing Street office said he would publish a proposal paper and outline for lawmakers the government's preferred option for replacing Britain's current nuclear submarine-based defense system. Britain's fleet of four nuclear-powered submarines, which are each capable of carrying up to 16 nuclear-armed Trident missiles are expected to end their operational life by 2024. Though some legislators had urged the government to try and extend the life of the current fleet and delay a decision, both Blair and his expected successor - Treasury chief Gordon Brown - pledged to deliver a recommendation to lawmakers by the end of this year. Blair's official spokesman, who speaks on condition of anonymity in line with government rules, said a special Cabinet meeting would be convened Monday to approve the text of the proposal paper. Lawmakers will be asked to vote on the proposal by March 2007, allowing three months for debate. Experts said Blair appeared certain to back a plan to build a new nuclear submarine fleet. Land or air based defenses were ruled out, as military advisers had decided they were too susceptible to attack.