MPs will be given a vote on extending the month-long lockdown beyond December 2, Downing Street has said.
The Prime Minister's official spokesman sought to reassure angry Conservative MPs that the new lockdown in England would automatically expire on 00.01 on Wednesday, December 2.
The spokesman gave a guarantee that Parliament would get a say on the next steps when the four-week lockdown ends.
But he failed to rule out keeping England locked down for longer if the virus is not under control.
England will be plunged into national lockdown once more from midnight on Thursday after Boris Johnson caved to pressure in the face of spiralling coronavirus rates.
People will be told to stay at home again bar exemptions for exercise, travelling to work and school, to shop for essential items and for medical or caring reaons.
MPs will be asked to approve the move on Wednesday, which would last for four weeks.
But the Prime Minister is facing anger from all sides over the plan, ranging from the severity of the restrictions to the delay to imposing lockdown measures called for by scientists.
Tory backbench leader Sir Graham Brady led criticism of lockdown, describing the restrictions on people's liberties as "evil".
The PM's official spokesman insisted MPs would get a vote, saying: "Yes, these regulations will automatically expire ahead of Wednesday, 2 December and MPs will have a vote on the proposed way forward."
The spokesman added: "We believe the package of tougher new measures which we introduced will allow us to bring the R rate down in such a way that we are able from December 2 to move back to that regionalised approach."
It comes as Mr Johnson was due to give a Commons statement on Monday afternoon, where he is likely to get a rough ride from his own MPs over the new lockdown plans.
He is expected to say: "Models of our scientists suggest that unless we act now, we could see deaths over the winter that are twice as bad or more compared with the first wave.
"Faced with these latest figures, there is no alternative but to take further action at a national level.
"At the end of four weeks, on Wednesday December 2, we will seek to ease restrictions, going back into the tiered system on a local and regional basis according to the latest data and trends."
The Prime Minister also faces criticism for not acting sooner, as one of the scientific advisors to the Government said "thousands of lives" could have been saved.
Professor Andrew Hayward, who sits on the Government's New and Emerging Respiratory Virus Threats Advisory Group, said the shorter lockdown called for by scientists in September would have saved lives and caused less economic damage.
"I think if we had chosen a two-week circuit-break at that time, we would definitely have saved thousands of lives," he told BBC Radio 4's Today programme.
"And we would clearly have inflicted substantially less damage on our economy than the proposed four-week lockdown will do."
