Cameron would have to step down early if re-elected - ally

By Andrew Osborn LONDON (Reuters) - British Prime Minister David Cameron would have to step down early if re-elected on May 7 to allow his Conservative Party to choose a new leader, one of his ministers said on Sunday, reigniting speculation on an issue Cameron wants to close. Iain Duncan-Smith's comments, on the eve of the official start of a campaign for the most unpredictable British election since the 1970s, appeared to contradict Cameron's own stance and will anger party strategists who want to focus public attention on the country's economic resurgence. Cameron surprised his ministers last week when he said he would not seek a third term if voters gave him a second mandate in May. The disclosure backfired, sparking a media frenzy about his successor and talk of him becoming a lame duck leader. Cameron, who has said he wants to serve a full five-year term if re-elected, had to deny during his final debate in parliament that he had weakened his own authority by talking about leaving and has since tried to draw a line under the subject. But Duncan-Smith, minister for work and pensions and a former Conservative leader himself, re-opened the subject on Sunday, saying Cameron would have to stand down before the end of the next five-year parliament to allow time for a leadership contest before an election due in 2020. "He does (have to stand down). But I have huge faith in the prime minister," Duncan-Smith told the BBC's Andrew Marr Show, adding that Cameron would still be able to serve "what essentially is a full term". "Of course there’ll be a (leadership) competition at some point. But I have to tell you that will be a competition on the back of a successful prime minister doing something that most prime ministers have never done before: saying I know when it’s time to go." Duncan Smith said he would be "sorry" to see Cameron quit. Cameron's aides said his determination to serve a full term if re-elected remained unchanged. The right-leaning Conservatives have been neck-and-neck in most opinion polls with the opposition centre-left Labour Party, though one poll on Sunday gave Labour a four percentage point lead. (Editing by Gareth Jones)