Boris Johnson says he will give MPs more time to debate Brexit deal but only if they agree to 12 December general election.
He said he expected the EU to grant an extension to his 31 October deadline, even though he “really” did not want one.
He urged Labour to back an election in a vote he plans to hold next week.
The EU is expected to give its verdict on extending Brexit on Friday.
If Brexit is delayed to the end of November, the PM will try to get his deal through Parliament again, the BBC understands.
If the delay is to the end of January, Mr Johnson will hold a Commons vote next week on a 12 December election.
If Labour agrees to the election, then the government says it will try to get its deal through before Parliament is dissolved for the campaign on 6 November.
Asked by the BBC’s Laura Kuenssberg what he would do if Labour refused to vote for an election, he said: “We would campaign day after day for the people of this country to be released from subjection to a Parliament that has outlived its usefulness.”
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