The government is facing calls from Tory backbenchers to drop the 2m (6ft) social distancing rule in England.
MPs, including former cabinet ministers Sir Iain Duncan Smith and Damian Green, say it is essential for the economy.
The government has said it is constantly reviewing its coronavirus lockdown guidance.
It follows the announcement of a further easing of restrictions in England, allowing single adults to stay at one other household from Saturday.
No 10 said the change aimed to help combat loneliness and that people were being trusted to observe the rules.
The relaxation does not apply to those who are shielding, or other UK nations.
Meanwhile, Labour leader Sir Keir Starmer has accused ministers of “mismanagement” over the reopening of schools, saying the government is putting the welfare and education of children at risk.
As the lockdown continues to be eased in England, there are fears in Westminster and the business community that keeping the 2m rule will significantly impede recovery.
Former Conservative Party leader Sir Iain has warned of dire economic consequences, with public transport running quieter than necessary and pubs, restaurants and cafes unable to stage a proper recovery or even open.
He has urged ministers to move to a 1m policy – in line with World Health Organization guidance already followed by countries including France, Denmark and Singapore.
“The number one and single most important priority to unlock the economy is getting the distance down to 1m,” Sir Iain told the Daily Mail.
“The hospitality sector simply can’t make a living at 2m.”
Mr Green told the BBC’s Newsnight scrapping the 2m guidance was the “single biggest change” the government should make in the coming weeks.
“I think that makes a huge difference to many parts of industry, particularly hospitality businesses, restaurants, pubs, and so on,” he told the programme.
“We’ve seen other countries do that, actually move from 2m to 1m, without any damaging effects so far.”
It comes amid continued debate over schools reopening in England, after it was confirmed most children would not return to classrooms until September.
Sir Keir urged the prime minister to act now to ensure that target could be met.
Writing in the Daily Telegraph, he said “creativity” was needed to utilise empty buildings, including theatres, museums and libraries, as makeshift classrooms.
Mr Johnson said there would be a national “catch-up programme” for pupils in England, but warned a September return date for all pupils would depend on whether progress continued to be made in controlling the virus.