Jeremy Corbyn has accused Theresa May of trying to "blackmail" Labour MPs into backing her EU Withdrawal Agreement after she threatened chaos if the UK crashes out without a deal.
But the Labour leader declared on Monday night: "The Labour Party will not be held to ransom."
Addressing the Parliamentary Labour Party (PLP) on the eve of the crucial Commons vote, Mr Corbyn predicted Mrs May's deal would be defeated and said the country should then have a general election.
Pressed on when he will table the no-confidence motion which he hopes will trigger an election, Mr Corbyn told MPs: "Don't be concerned, it's coming soon."
A Press Association source said the PLP meeting was "calm and supportive", and that Mr Corbyn had dealt with a number of "respectful" queries from MPs about the party's next steps if it fails to secure a general election.
Mr Corbyn is under increasing pressure from the party's huge membership to back a second vote on Brexit.
But the source stressed a second referendum was only one of a number of options which would be on the table for Labour - alongside seeking a different Brexit deal in line with the party's own priorities.
Mr Corbyn made clear in the behind-closed-doors meeting that he still has concerns about the "neo-liberal" direction the EU has taken, which led him to campaign in the 2016 referendum on a platform of "remain and reform".
Meanwhile, Mrs May also addressed a gathering of Conservative MPs.
She urged Tory MPs to back her Brexit deal with a warning they need to keep Jeremy Corbyn "as far away from Number 10 as possible".
Following her Commons statement on Monday, the Prime Minister addressed the private meeting at Westminster for more than 30 minutes.
Children's minister Nadhim Zahawi, who was at the meeting, said she had told them they needed to deliver on Brexit while preventing a Labour government.
"She said we have got to keep Jeremy Corbyn as far away as possible from Number 10. To do that, we have got to come together."
It came against a backdrop of increased tension around Parliament, with hundreds of Leave and Remain supporters gathering outside on Monday. Numerous people became involved in heated bust-ups as the nation builds up to Tuesday's crucial Commons vote.
Reporting by Press Association.
