Johnson said in a letter to opposition Labour leader Jeremy Corbyn on Thursday he would give parliament more time to approve his Brexit deal by Nov. 6 but lawmakers must on Monday back a December election, Johnson's third attempt to try to force a snap vote.
"Prolonging this paralysis into 2020 would have dangerous consequences," he said. "If I win a majority in this election, we will then ratify the great new deal that I have negotiated, get Brexit done in January and the country will move on."
Corbyn said he would wait to see what the EU decides on a Brexit delay before deciding which way to vote on Monday, repeating that he could only back an election when the risk of Johnson taking Britain out of the EU without a deal to smooth the transition was off the table.
It is not clear how Corbyn would respond if the EU makes no decision on a date on Friday.
