A leadership contest will be held Monday evening.
Sir Graham Brady said he had received enough letters of no confidence to force a vote on the prime minister's leadership.
Conservatives are required to submit letters. Insider was told by sources that more than 60 had done it.
Brady said there would be a vote on Monday. The prime minister described the vote as a chance to "draw a line and move on"
He stated that the threshold for a vote of confidence in the leader of the Conservative Party had been exceeded.
The ballot will be held between 18 and 20 June.
Brady told journalists that the vote would take place in the House of Commons and that the results would be announced later.
He told the prime minister that the threshold had been reached.
He agreed with me that the vote should happen as soon as possible, in line with the rules that we have in place.
Sources had claimed last week that some of Brady's colleagues had asked for it to not be until after the celebrations.
"Tonight is a chance to end months of speculation and allow the government to draw a line and move on, delivering on the people's priorities," said a spokesman for the prime minister.
The PM will remind the MPs that there is no more formidable political force if they focus on the issues that matter to voters.
A letter of no confidence was published by another senior member of parliament.
Jesse Norman, a former Treasury minister, went public with an excoriating letter against Johnson.
It included plans to send failed asylum seekers to Rwanda, as well as the so-called "partygate" scandal in which Johnson and others broke rules to hold parties.
—Jesse Norman (@Jesse_Norman) June 6, 2022
There is more to come.