Boris Johnson will announce on Monday whether or not plans to ease restrictions from later this month will go ahead.
Earlier this year the Prime Minister said step 4 of the roadmap out of lockdown - which would see the end all legal limits on social contact - would happen no earlier than June 21.
However there are now concerns about the highly transmissible Delta variant with the number of Covid cases in the UK and England now starting to rise.
There are reports that the Prime Minister will instead put the final easing of controls on hold for up to four weeks.
It could mean that lockdown lifting will be put back to July 19.
The move would be a bitter blow for many businesses, particularly in the hospitality sector, which had been pinning their hopes on a full summer reopening.
Speaking in Cornwall on Saturday, a downbeat Mr Johnson acknowledged that the rise of the variant was a matter of “serious, serious concern”.
With infections and hospital admissions both rising, he said that it was not yet clear to what extent that would feed through into more deaths.
However, in order to ensure the final lockdown lifting was “irreversible”, he said that it may be necessary to give the vaccines “extra legs” in the race against the virus.
Studies have shown that people who have received only one dose of the vaccine have significantly less protection against the Delta variant – first identified in India – than those who have had two jabs.
Public health officials believe a delay would also give more opportunity to control the spread using surge-testing techniques which proved successful in Bolton, which was the first Delta variant hotspot.
Follow the latest updates below.