article: Commons Leader Chris Grayling, who backs a Leave Vote, told the BBC: "He must stay, I want him to stay." Northern Ireland Secretary Theresa Villiers told Sky he was the "right man to take us out of the European Union". It comes after former chancellor Ken Clarke suggested the PM "wouldn't last 30 seconds if he lost the referendum". Although Mr Cameron is campaigning for the UK to remain in the European Union, many Conservative MPs, and some members of his own cabinet, are campaigning to leave. EU referendum: In depth The UK's EU vote: All you need to know EU for beginners: A guide UK and the EU: Better off out or in? A-Z guide to EU-speak Who's who: The Vote Leave team Who's who: The Remain campaign Mr Clarke, a veteran pro-European Conservative, told the BBC last week it was "farcical" to suggest Mr Cameron would be able to remain prime minister if the UK votes to leave the EU in the 23 June referendum, despite campaigning to remain in. He predicted the party would be "plunged into a Conservative leadership crisis". But Commons leader Mr Grayling told BBC One's Andrew Marr Show: "I actively want David Cameron to stay, not only because he's a very good prime minister, but because he actually has got the relationships we need around Europe to build the negotiating process. "It would be disastrous, in my view, for the Leave cause if we vote to leave and then we get distracted by a Conservative leadership contest. He must stay, I want him to stay." He said the PM could be "part of a team" which would negotiate Britain's exit from the EU but added "it needs people who want to leave in that team as well". David Davis, the former shadow home secretary, told the programme he believed the PM could stay on but would have to appoint someone "who believed in the negotiation" to lead exit talks. And Northern Ireland Secretary Ms Villiers, who is also backing the Leave campaign, told Sky News: "It's vitally important that he stays regardless of the vote in the referendum because he's a great prime minister". Mr Cameron himself has said he would stay on as prime minister, even if he ended up on the losing side. But Suzanne Evans, the former UKIP deputy chairwoman who is on the board of Vote Leave, said Mr Cameron had made a "terrible job" of his EU negotiations ahead of the referendum and she believed he should resign, if the UK votes to leave. She told Pienaar's Politics: "I don't particularly want him to be negotiating on our behalf." The official referendum campaigning period began on Friday and rows have continued about the potential impact of leaving the EU on trade, the single market and farm funding. Labour's Yvette Cooper warned it could cost "Â£100bn worth of trade" and lead to a loss of manufacturing jobs adding: "It's working class people across Britain who will be hardest hit if we end up losing those jobs". And French economy minister Emmanuel
summary: David Cameron should stay on as PM to lead negotiations if the UK votes to leave the EU, two cabinet ministers have said.