Elections 11 April 2016 David Cameron reminds the Conservatives of the gap he will leave David Cameron reminded observers of his abilities – and the Conservatives that they'll miss him. Photo: Getty Sign UpGet the New Statesman's Morning Call email. Sign-up David Cameron reached his “Best Before” date the second he told the BBC’s James Landale that he would step down before the 2020 election – from that moment, power has been ebbing away from the Prime Minister and towards whichever one of his rivals is currently in the ascendant. Cameron abhors the frequent reshuffles that characterised the New Labour era, which means that even if his second term is not cut short by defeat in the referendum and he achieves his aim of staying in power until 2019, he realistically has only one Cabinet reshuffle left in him, which means his capacity to either reward or punish his MPs is limited. The last few weeks have looked at time to be bringing him dangerously close to his “Sell By” date, but his performance today in the House of Commons staved off the forces of entropy – for now, at least. If Remain does go on to win the referendum, we may look back on Cameron’s difficult few weeks in the same way we do on the abortive plot to replace Cameron with Adam Afriye in January 2013 (“Who’s Adam Afriye?” I hear you ask. Well, indeed.). But it was the performance of the man – Sajid Javid – who spoke after him from the government side of the House that highlighted the concern troubling some Conservative MPs, namely that Cameron’s reluctance to reshuffle, as well as making the Conservative whips’ lives harder – with a working majority of just 16 at the moment, getting the government’s business through can be a tricky business – it has left the Conservatives’ top ranks less fresh than they should be. Stephen Crabb is tipped for bright things at the Department of Work and Pensions, but if the work of untangling Iain Duncan Smith’s botched reforms takes his career down with it, the pool of potential challengers from the Conservatives’ younger generation will become very shallow, although both Nicky Morgan from the left and Dominic Raab from the right will likely run from the 2010 intake. There wasn’t anything particularly bad about Javid’s performance, although it will feed the sense among Conservative MPs that he is not as impressive as his backstory. But as I wrote yesterday, for all Cameron’s handling of his tax affairs has put unnecessary pressure on him and his party, he remains his party’s biggest asset and it’s difficult to imagine any of his possible successors doing as well: Boris Johnson has never been a natural Commons performer, and the whole row feels designed to showcase George Osborne’s weaknesses. (Although don’t rule out the ability of Theresa May, largely absent from recent leadership speculation, to pull off an unexpected revival, particularly if Osborne’s stock fails to recover from its present lows.) It comes back to an unnoticed line from Matthew Parris’ recent hatchet job on Johnson, widely shared both outside and inside Westminster and particularly enjoyed by the Mayor’s rivals: “the Tory party is running out of future prime ministers”. Not that it matters to most Conservatives, who regard the next election as a formality regardless of who they have at centre-forward as long as Jeremy Corbyn or a likeminded politician is at the helm of the Labour party. But things could change quickly - don't forget that just over a decade ago, Tony Blair was Prime Minister and most expected Gordon Brown, his successor, to easily defeat David Davis or Liam Fox at the next election. The Conservatives' relatively slim bench could prove a problem sooner than most in Westminster think. While Cameron may not have reached his Sell By date yet, it should concern thinking Conservatives that it is not immediately apparent that they have a product of equivalent quality left in the shop. › Should we publish everybody’s tax return? Stephen Bush is political editor of the New Statesman. His daily briefing, Morning Call, provides a quick and essential guide to domestic and global politics. Subscribe For more great writing from our award-winning journalists subscribe for just £1 per month!