Boris Johnson will face Tory MPs on Tuesday in an effort to quell unease over his route out of lockdown ahead of Commons votes on the plan.
The Prime Minister will speak to the Conservative backbench 1922 Committee to defend the Government’s approach, which will see some restrictions remain in place in England until at least June 21.
On Thursday MPs will be asked to approve the regulations for the road map and extend some of the emergency powers in the Coronavirus Act for a further six months.
Tory former chief whip Mark Harper, leader of the Covid Recovery Group of lockdown-sceptics, said the regulations “raise a number of key questions” and again suggested that ministers were attempting to move the goalposts before ending the curbs on freedom.
The Prime Minister’s press secretary Allegra Stratton said: “As you would expect, the Prime Minister is using every opportunity when he meets his Conservative MPs to make the case.”
She said Mr Johnson believed “this is a cautious but, if we do it right, irreversible road map” which would take time because of the need to assess the impact of each measure.
The Government’s plan would see shops and pub beer gardens open on April 12 at the earliest, with indoor hospitality allowed from May 17 if all goes to plan and the final stages of lockdown being lifted on June 21.
“So, taking the time to do it in the way that we are doing, with the five-week review points (between stages), means that we are sure at every point that the loosening is the right thing to be doing,” Ms Stratton said.
“That’s why it is taking its time, because we want to make sure we are doing the right thing.”
In a move which could win over Tory MPs uneasy about the continuation of the Coronavirus Act, the Government indicated it will remove or suspend measures which are no longer required.
They include provisions on emergency volunteers which could have come into force if the delivery of health services was at risk and the end of an extension to time limits for retaining fingerprints and DNA profiles.
But Mr Harper said the road map regulations expire on June 30, rather than June 21 and “however minor this seems, it may add to concerns that goalposts are being moved”.
The planned six-month extension to the Coronavirus Act was in “fundamental contradiction” to the road map because it would go far beyond the June date.
“The Coronavirus Act contains some of the most draconian detention powers in modern British legal history, and if ministers want to renew its provisions, they must demonstrate they are proportionate, reasonable and grounded in evidence,” he said.
“For any and every temporary measure that the Government wishes to retain, the burden is on them to set out, in Parliament, a very clear justification.”
The measures are likely to comfortably pass, with Labour not expected to oppose them.
But Mr Harper said: “No matter how Parliament votes this week on the temporary provisions of the Coronavirus Act, the financial support packages will remain in place regardless.
“So I hope that the Opposition starts asking the reasonable questions about why significant police powers are going to be extended until October, three months beyond the end of the road map.
“If the Government wants Parliament to pass a law this Thursday making it illegal for families to celebrate Easter together, ministers should be prepared to say that they want these laws to be consistently policed and enforced.
“It is damaging to pass laws that aren’t enforced, and unfair to place police officers in an impossible position.”
Mr Johnson on Monday warned that a third wave of cases in Europe risked crossing the Channel to the UK.
Mr Harper said: “Case rates in the EU are concerning, of course, because the EU, regretfully, hasn’t had as much success as us in vaccinating EU citizens.
“But the whole point of vaccinating people at such speed is to prevent Covid infections from causing serious disease, hospitalisation and death.
“Lockdowns and restrictions cause severe harm to people’s health, wellbeing and livelihoods and it’s vital we end them as soon as it is safe to do so.”