Video report by ITV News political correspondent Paul Brand
Iain Duncan Smith has called for the Universal Credit (UC) waiting time to be cut from six weeks to a month.
Former work and pensions secretary Mr Smith, who first proposed UC, told ITV News it was not his idea to make the wait that long.
Ex-Tory leader Mr Smith said the additional waiting weeks were not "wholly necessary".
His comments on Monday came after the Government, under increased pressure over UC, caved in to demands over abolishing call charges to the UC helpline.
Some claimants were being charged up to 55p a minute to contact the service.
Elsewhere, the Smith Institute has published a report indicating that on average UC claimants are £150 in rental arrears because of the delay to payments.
Speaking to ITV News, Mr Duncan Smith washed his hands of any responsibility for the six-week wait.
"The idea of the extra days was not something which I or my colleagues came up with," he said.
"It was a Treasury matter at the time and I think it's certainly worth them reviewing that to see whether or not they can get rid of the waiting days - they're not wholly necessary."
Some Tory MPs are believed to be in favour of the waiting time being slashed from six weeks.
But the Government has insisted there are already advance payment options in place for people struggling with delays.