Boris Johnson could face a Tory backbench rebellion as MPs are set to vote on the Covid-19 rule of six this week.
The social distancing rule means that any gathering of more than six people – indoors and outdoors – is illegal in England.
Downing Street confirmed on Monday that the Commons will vote on the measure on Tuesday.
It comes amid growing anger from Tory backbenchers, who oppose more intervention and restrictions from the state.
The prime minister’s official spokesperson urged tory MPs to back the motion, telling reporters: “He would urge all MPs to vote for it.
“The measures we are bringing forward are there for a specific purpose and that is to help us to control the spread of the virus and protect the NHS.”
The spokesperson added: “He understands many of the frustrations that people have but as the prime minister, he has to take a course of action that prevents the further spread of the virus and therefore protects the NHS and protects lives.
“What we are seeking to do is get the right balance between protecting lives and livelihoods, which is why we are also trying to keep as much of the economy moving as we can.
“In terms of the rule of six, it gives clarity to the public and is a sensible and helpful step in helping us to control the spread of the virus.”
The vote follows around 40 MPs writing to the prime minister last week to warn him new government measures should have parliamentary scrutiny.
Would-be rebels have been coalescing around Graham Brady, chair of the powerful 1922 committee of Tory MPs, who has warned the government it cannot “rule by decree” during the pandemic.
With an 80-seat majority, however, it is unlikely rebels will have the numbers to defeat Johnson.
It also follows a huge jump in the number of infections after a computer glitch meant some 16,000 lab-confirmed cases of Covid-19 from the previous week were recorded late.