Labour is planning a vote of no confidence in Boris Johnson to try to force him out of Downing Street immediately, because of concerns he might abuse his role as caretaker prime minister.
Angela Rayner, deputy Labour leader, said Johnson was “engulfed in sleaze” and should not be allowed to continue in office.
Johnson announced on Thursday he was standing down as Conservative leader, but wants to stay as prime minister until his successor is appointed, probably in early September.
Some Conservative MPs have called for Johnson to leave immediately, claiming his authority has been irrevocably tarnished by scandal.
However most Tory MPs have accepted Johnson will remain in place until his successor as party leader is chosen and are looking to his newly appointed cabinet to keep him on a tight leash.
Johnson told the cabinet on Thursday that he was simply minding the shop and that while normal government business should continue there would be no “novel” ideas or departure from existing policy.
Rayner said she did not trust Johnson and that if Tory MPs do not remove him from Downing Street immediately, then Labour would move a vote of no confidence next week in both the prime minister and his government.
Such a motion would almost certainly be defeated in the House of Commons by Conservative MPs, who would not want to hand a political victory to Labour.
Labour said it would expect Johnson to resign as prime minister if he lost the confidence vote, but added that following the repeal of the fixed term parliaments act a defeat would not force a general election.
James Cleverly, the new education secretary, told the BBC that Johnson and his new cabinet would observe the proprieties and not take any decisions “that would bind the hands of our successors”.
For example, Johnson’s hopes of making a major economic speech, trailing big cuts to corporation tax and income tax, have been dashed and will now not take place.
However Cleverly said decisions on issues such as public sector pay could be taken to provide certainty in professions such as teaching. Contentious legislation to scrap parts of Johnson’s Brexit deal, covering Northern Ireland’s trading arrangements, is expected to continue through its Commons stages.
Other contentious legislation, including a financial services bill that would overhaul City of London regulation, are also expected to proceed but the pace of reform may be affected by the departure of chancellor Rishi Sunak and economic secretary John Glen.
The principal check on Johnson’s power will come from the cabinet, although Simon Case, cabinet secretary, will also have a role in ensuring that new policy is not authorised by a lame duck administration.
“He has to set down some rules, he has to draw some lines,” Sir David Normington, former permanent secretary at the Home Office, told the BBC.
Asked whether he thought Case would be able to rein in Johnson, he said: “I’m a little doubtful about it, he has presided over a decline in standards.”
He added: “He’s had a very difficult prime minister to deal with, but he’s sometimes seemed like the bystander at a car crash. This is the moment for him to step up.”
Meanwhile Johnson and his wife Carrie have decided not to press ahead with a much-criticised wedding celebration at Chequers, the prime minister’s country retreat, on July 30.
People close to the couple said they would move the event to another location. Johnson had been accused by Rayner of trying to “cling on for the next couple of months” so he could have the party at Chequers.
Tory MPs will on Monday elect a new executive to the 1922 committee of backbench Conservatives, which will then finalise the rules for the party leadership contest.
They are expected to rubber-stamp a two-stage process. In the first stage, Tory MPs will whittle down a long list of leadership candidates to a shortlist of two, to be agreed before the Commons summer recess on July 21.
The two candidates will then tour the country, making their case to the party’s members, who will have the final say.
The new Tory leader is expected to be chosen before the Commons returns on September 5.