Labour has repeatedly warned that problems must be fixed before the plans go ahead this month. Twelve Tory MPs have also written to Work and Pensions Secretary David Gauke highlighting the dangers.
Mr Gauke is expected to announce some minor tweaks to the scheme today, rather than unveiling any substantive reforms.
Speaking at a Huffington Post fringe meeting at the Conservative Party conference yesterday, he said more than 50 per cent of claimants were receiving emergency cash advances from the Department for Work and Pensions (DWP) while waiting the standard six weeks for applications to be processed.
But the Citizens Advice charity warned that one in 10 people waits 10 weeks for their first payment. The Trussell Trust charity has also reported a 67 per cent rise in foodbank referrals.
Nonetheless, Mr Gauke said yesterday: "If I looked at it and thought this is a mistake, I would be attempting to do something to stop it. But I don't."
Prime Minister Theresa May, who has been reviewing the proposals with Mr Gauke, admitted there had been "issues and problems" but insisted that UC expansion was "the right thing to do."
Shadow secretary of state for work and pensions Debbie Abrahams branded the six-week wait a "punitive policy."
She added: "We are yet to see anything that amounts to action to support the 13 million people living in poverty in Britain."
The nationwide rollout to new claimants is due to be completed by the autumn of next year.
Citizens Advice analysis reveals that seven million households will receive UC by 2022 and more than half of them will be in work.