“Soundings off” against Prime Minister Theresa May have to stop, former cabinet minister Justine Greening has told her Tory colleagues.
Ms Greening, who lost her job as education secretary in the reshuffle, said the PM needed support for “challenging” Brexit talks.
She also said university maintenance grants, replaced with loans by the Tory government, should be restored.
And she called for a re-think over student loan interest rates.
Ms Greening’s first interview since she lost her job came amid backbench criticism of Theresa May about Brexit and policy direction.
Over the weekend one Tory MP tweeted: “We need to get a grip and lead” while another urged “less policy making by tortoise”.
There has also been criticism from Conservative Eurosceptics that the UK will stay in the EU “in all but name” after Brexit in March 2019.
Speaking on BBC Radio 4’s Today programme, Ms Greening said she rejected the “tortoise” accusation and that she remained a “firm supporter” of Mrs May.
“The soundings off have to stop,” she said.
During the reshuffle earlier this month, Mrs May had wanted to move Mrs Greening to the Departure for Work and Pensions, but she refused and quit the government instead.
She has since been accused by the PM’s former adviser Nick Timothy of blocking moves to reduce tuition fees.
Asked about this, Ms Greening said she had opposed a review into cutting the maximum level of fees that can be charged, suggesting this would have kicked the issue “into the long grass”.
And she said it was “wrong” that poorer students were the main losers from the scrapping of maintenance grants.
The £3,387 grants towards living costs were available to students from families with annual incomes of £25,000.