A Cabinet minister has admitted that the implementation of the Universal Credit system was "pretty lamentable" in its first two years.
In highly critical comments, Francis Maude told ITV News it was "very regrettable" so much money had been wasted.
The Conservative Cabinet Office minister, who had to send in troubleshooters from the Government Digital Service to salvage the system, denied he'd fallen out with the Work and Pensions Secretary, Iain Duncan Smith.
But he refused to endorse Mr Duncan Smith's twin track approach in which the old and new systems run alongside each other.
"There were some major problems, the implementation was pretty lamentable," he said.
He defended Mr Duncan Smith for acting "quickly and effectively" once problems came to light, but added:
It's recognised there have been significant write-offs. There was a lot of money wasted in the very poor implementation of the project over its first two years and this is very regrettable.
Asked whether he thought it was a good idea to pursue a twin track approach, keeping the old system running while the new was being developed, he said:
"The Department for Work and Pensions were concerned they get the numbers through to have the full learning, they took a decision they should go ahead with the twin track approach and we need to work to make sure that can be successful."
Was this really efficient? I then asked. He replied "They took a view on how it should be done which obviously we've collectively agreed"
"I obviously support what the Government collectively agreed."
When I asked whether he personally had any reservations, he said:
"I am going to tell you again I support what the Government collectively agreed."
The Work and Pensions Department has accepted that £34 million was wasted during the implementation of the Universal Credit system, before a technical support was called in to redesign the IT.
Watch Libby Wiener's report on how what were initially dismissed as "teething problems" with Universal Credit have been revealed as much more serious: