Boris Johnson has said he will give MPs more time to debate his Brexit deal, but only if they agree to a 12 December general election.
The prime minister told the BBC 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.
EU leaders are expected to give their verdict on delaying Brexit for up to three months, on Friday.
Commons leader Jacob Rees-Mogg told MPs the government would on Monday table a motion calling for a general election.
Under the 2011 Fixed-Term Parliament Act, two-thirds of MPs must vote for a general election before one can be held.
Shadow leader of the House Valerie Vaz said Labour would back an election “once no-deal is ruled out and if the extension allows”.
Labour would offer the PM its support for a “proper timetable” for the Brexit bill to allow MPs to scrutinise and amend it, she added.
In a letter to Labour leader Jeremy Corbyn, Mr Johnson says his “preferred option” is a short Brexit postponement “say to 15 or 30 November”.
In that case, he writes, he will try to get his deal through Parliament again, with Labour’s support.
The prime minister adds that he “assumes” Mr Corbyn “will cooperate with me to get our new Brexit deal ratified, so we leave with a new deal rather than no deal”.
If, as widely expected, the EU’s Brexit delay is to the end of January, Mr Johnson says he will hold a Commons vote next week on a 12 December election.
If Labour agrees to this, the government says it will try to get its deal through before Parliament is dissolved for the campaign on 6 November.