WHEN, in 2010, Iain Duncan Smith announced a plan to replace Britain’s thicket of welfare benefits with a single, simple “universal credit”, he was not modest about its potential. The new system, the welfare secretary told the Conservative Party conference, would be “the biggest reform of the welfare system in a generation”. It would be nothing less than an entirely new social contract between taxpayer and claimant. Pulled in front of a Parliamentary committee on December 9th, Mr Duncan Smith struck a less messianic tone: the best he could say of his scheme is that it is “no debacle”. The project, one of the coalition government’s most ambitious public-sector reforms, is years behind schedule, mostly thanks to problems with its computer systems. The entire project may collapse, or be cancelled by a less determined successor to Mr Duncan Smith.

The laudable aim of the universal credit is to unpick the perverse incentives created by the welfare system. People claiming benefits can find that working a few more hours hardly improves their lot, or even makes it worse, so quickly are payments withdrawn. Under universal credit, all benefits will be combined into one and clawed back at a rate of 65% of take-home pay. This ought to encourage more people to work. In a separate reform, earnings data, previously collected annually, will be quickly submitted to the government when wages are paid, ensuring accurate welfare payments.

Mr Duncan Smith at first said that all new claimants would receive universal credit beginning in October 2013, and that everybody who receives welfare would be on the system by the end of 2017. That deadline quickly slipped. In March the government still expected that 1.7m people could be moved onto the new system by the end of 2014. Now at most a few tens of thousands will be (see chart). This implies that almost all of the work to move 5.8m claimants from the old system to the new one by 2017 will be done in just two years. Some £40m ($66m) spent on software has been written off and another £91m worth will be out of date within five years.

The entire project has been “a classic case of ministerial overreach”, says Colin Talbot, an expert in policy-making at the University of Manchester. Mr Duncan Smith came to office in 2010 with a big plan but little idea of how difficult it would be to enact. Since then he has made some amends—restarting the project and hiring Howard Shiplee, a high-profile official who helped to organise the Olympics. But Mr Talbot says that further delays are almost inevitable. The system cannot currently handle claims by couples or people with children. Processing millions of claimants, often with extremely complicated family lives, in just two years would represent spectacular progress. Indeed, Mr Duncan Smith already admits that some 700,000 disabled claimants will take longer than that to move onto the credit.

The biggest threat to Mr Duncan Smith’s vision is not technical but political. Under the original plan, most of the work would be done by 2015, the year of the next general election. Now it has all been pushed into the next parliament—when it is not certain that Mr Duncan Smith will be in office. George Osborne, the chancellor of the exchequer, is said by almost everyone to doubt the welfare secretary’s vision. The Labour Party supports the new system but has lots of questions about the details. If it is not ready by 2015, a new government might well ditch it.

If so, one of the coalition’s most ambitious plans will have failed. Welfare reform will be limited to crude cost-saving measures, mostly introduced by Mr Osborne. A cap of £26,000 on the amount of money a single workless family can receive is wildly popular, but affects just 28,500 households. The most dramatic single policy may well prove to be a decision to increase all benefit rates by less than the rate of inflation—which could send poverty rates soaring and do nothing to get people into work. That is an unhappy conclusion for a government that promised radicalism.