Video report by ITV News Political Reporter Shehab Khan
It comes amid a growing revolt from within Mr Johnson’s party, with at least 40 Tory MPs having now publicly called for Mr Cummings to be sacked or to resign.
And a YouGov survey for The Times showed the Conservative lead over Labour dropped by nine points during the Cummings saga, as support for the Government fell four points to 44% with Labour rising five points in the week to Tuesday, to 38%.
Senior ministers have expressed public support for the defiant adviser but there are reports a number of Cabinet members have privately called for him to be ousted from No 10.
Housing Secretary Robert Jenrick said “the moment has come for us to move on” from the row surrounding Mr Cummings.
“Although this issue is important and many people disagree with the way that Mr Cummings behaved, we now need to focus on the wider issues of controlling the virus, reopening and restarting the economy ,” he added.
Mr Jenrick confirmed the government would not be holding a formal review of coronavirus penalty fines issued to parents travelling for childcare during the lockdown, after Mr Cummings made a trip to his parent's house so he could be closer to childcare, should he and his wife become incapacitated by Covid-19.
“Imposing a fine is a decision for police and so it’s right we leave this at their discretion under the law, they have their own guidance, issued by the National Police Chief’s Council, and that gives them a degree of discretion, respecting the fact that individual circumstances are different and there are particular challenges faced by some people in society, not least parents with children.
“It’s right we respect the police’s right to impose fines if they wish to.”
But Shadow Foreign Secretary Lisa Nandy told ITV News “it’s becoming increasingly clear that people don’t have that level of confidence in the government and what they’re being told.”
“We said that the PM needs to urgently answer questions about the inconsistencies in the account that emerged over the weekend and if he can’t answer those questions then he needs to consider whether Dominic Cummings’ position is tenable,” she added.
Mr Johnson’s appearance via video link at Wednesday’s Commons Liaison Committee hearing has been tinged with controversy over the fact the PM will only briefly be quizzed on the Cummings affair.
MPs will have a maximum of 20 minutes in a 90-minute session to probe the situation when Mr Johnson appears before the committee.
ITV News Political Correspondent Carl Dinnen says people will be asking Boris Johnson about the Dominic Cummings' row 'for some time to come'
Asked about the situation regarding Mr Cummings, Liaison Committee chairman Sir Bernard Jenkin told the PA news agency: “I have got no intention of preventing any subject any member of the committee wants to raise.”
The comment follows controversy over Sir Bernard’s appointment to the committee chairmanship, with some MPs saying he is too close to the Prime Minister.
Sir Bernard insisted the format for the session has been agreed by the committee.
Also among those questioning the PM will be Labour chairwoman of the Home Affairs Committee Yvette Cooper, and Tory chairman of the Health Committee Jeremy Hunt.
The other MPs set to question Boris Johnson at the Liaison Committee:
Mr Cummings said he had driven to Durham to isolate in a property on his father’s farm because of concerns over care for his four-year-old son if both he and his wife were incapacitated by Covid-19.
But a growing number of Conservative MPs have voiced their frustration over Mr Cummings after he expressed “no regrets” about his trip to Durham.
Tory grandee Sir Roger Gale said the Conservative backbench 1922 Committee should make it clear to the PM his adviser should go.
“The time I think has come for Mr Cummings to resign or for the PM to dispense of his services,” the North Thanet MP told the PA news agency.
“There are people on the 1922 executive who are courageous, and that’s their job.
“They are elected to tell the PM what he needs to hear, not what he wants to hear.”