UK 5 July 2017 David Cameron defending austerity is not a good look for the Tories Theresa May signed away the argument when she agreed that deal with the DUP. Photo: Getty Sign UpGet the New Statesman\'s Morning Call email. Sign-up Party like it's 2015! David Cameron is back and making the case for austerity. Opponents of spending restraint are "selfish", the former PM harrumphed at a speaking engagement in South Korea (fee: undisclosed). "The opponents of so-called austerity couch their arguments in a way that make them sound generous and compassionate," he pronounced, "They seek to paint the supporters of sound finances as selfish, or uncaring. The exact reverse is true. Giving up on sound finances isn't being generous, it's being selfish: spending money today that you may need tomorrow." Park the economics for a moment, the politics haven't worked out too badly for the European centre-right since the financial crisis. One of the errors of the Conservative campaign, at least according to many of Cameron's allies, was in abandoning the austerity argument. Can the Tories recover their mojo by resuscitating the old hits? ("Its Hurting But It's Working" feat. T.Pain Hammond? "The Mess Labour Left" by Amb3r? Suggestions to the usual address.) There are a couple of problems with Cameron's message. The first, of course, is the messenger: a wealthy man emerging from his £26,000 shed to give a well-paid speech talking about the need for a pay freeze isn't a good look for the Conservative Party right now. The second is that the Conservatives signed away the austerity argument when they signed that deal with the DUP. You can't win political support for spending restraint in England, Scotland and Wales while turning on the taps in Northern Ireland. Now, of course, it's true that Northern Ireland is the poorest part of the United Kingdom and badly needs the extra investment that the £1.5bn will bring. It's true, too, that £1.5bn is a drop in the ocean compared to the £754bn that the British government spends every year. (To put it in perspective, the NHS in England alone spends £1bn every year on missed appointments.) The problem with that first line is that Northern Ireland isn't getting extra money because it's the poorest part of the United Kingdom but because the Conservatives lost their majority, and everyone knows that. It's true, too, that as far as government spending goes, £1.5bn isn't worth writing home about. But that's also true of the small deficit Labour was running before the financial crisis, and look at how much damage that's done to their reputation for sound financial management. May's election campaign lost the Conservatives their majority – but her public accord with the DUP has defanged their most effective political argument, not just for the life of this parliament but for the foreseeable future. › “Theresa May isn’t cool”: do the Tories need their own Momentum? 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. He also co-hosts the New Statesman podcast. Subscribe For daily analysis & more political coverage from Westminster and beyond subscribe for just £1 per month!