Boris Johnson is coming under pressure to appear before the House of Commons on Thursday to set out his Brexit strategy.
The new Conservative leader’s camp are yet to confirm whether Mr Johnson will face MPs on the only day remaining to him before parliament breaks up for its summer recess.
Conservative former cabinet minister Justine Greening said that the success or failure of Johnson’s premiership could be determined in the next few days and it would be “far too late” for him to wait until September before facing MPs.
After being appointed prime minister on Wednesday afternoon, it would not be enough for him to set out his plans in speeches away from Westminster, she said.
Because of the timing of the Conservative leadership election, Mr Johnson will take office little more than 24 hours before parliament’s summer recess begins on Thursday.
MPs are not due to return until 3 September - 59 days before the scheduled date of Brexit - and if Mr Johnson chooses not to make a statement he will not have to address the Commons until his first session of prime minister’s questions on 5 September.
Ms Greening told The Independent: “For most prime ministers, it is their first 100 days that count. For Boris it is the first 100 hours.
“It is vital he comes to Parliament to set out his Brexit strategy, not only to MPs but to the country.
“He also needs to set out a wider strategy for how he plans to get opportunity to communities that have been locked out of it for far too long.
“Britain is in the midst of a crisis on Brexit and Boris, as the new prime minister, must now set out how he plans to break the Brexit deadlock that led to Theresa May’s government failing so dramatically.”
Labour MP Tonia Antoniazzi, a leading supporter of the People’s Vote campaign, said: "Boris Johnson won the support of 0.1% of the population to become leader of the Conservative Party, but he has no mandate from the people for his policies of an extreme Brexit or even no-deal.
"He has to submit himself to parliamentary scrutiny and that means, at a minimum, coming to the House this week to answer questions on what he's up to. He cannot be allowed to slink off into the recess without answering MPs. He is going to have to learn he is accountable to Parliament and will ultimately have no choice but to hand the final say on Brexit back to the people."
