Labour will table a motion of no confidence in the government on Tuesday after it was confirmed Boris Johnson will remain prime minister for another eight weeks.
The move comes after the 1922 committee of backbench Tory MPs announced the timetable for the party’s leadership election on Monday evening.
The first round of voting will take place on Wednesday, with losing candidates dropping out after each ballot until just two are left.
They will then take part in a series of hustings across the UK, with the winner being announced on September 5.
Johnson will remain in post until his replacement is chosen by Tory members.
Following the PM’s announcement last week that he was standing down, angry Tories – including former party leader John Major called for him to leave Number 10 straight away.
Keir Starmer said Labour would table a vote of no confidence in the government in a bid to force Johnson’s immediate removal – a move which could potentially lead to a snap election.
The Labour leader said: “If they don’t get rid of him then Labour will step up and bring a vote of no confidence.
“He needs to go. He can’t cling on. They cannot inflict him on the country for the next few months.”
HuffPost UK understands Labour will table the motion tomorrow, with MPs expected to debate and vote on it on Wednesday.
The motion is certain to be defeated because it will not be supported by Conservative MPs.
But a Labour source said: “It will put the squeeze on backbench Tories to either vote for him, and be hypocrites, or back Labour, admitting we were right.
“Do all those Tory leadership candidates really want to be answering that question next week? They know he needs to go.”