Boris Johnson attacks Jeremy Corbyn for blocking a general election
The PM will accuse Jeremy Corbyn of "a cowardly insult to democracy" later for not backing a general election.
Boris Johnson - who sources say regards this as the first day of an election campaign - will say Mr Corbyn is denying the right of people to have their say.
On Wednesday, MPs blocked Mr Johnson's plan for an early election.
Shadow chancellor John McDonnell said Labour wanted an election but their priority was stopping a no-deal Brexit.
He also acknowledged there were splits in the party about the timing of a general election, saying that the leadership was in contact with legal experts and other opposition parties about what to do.
Speaking on BBC Breakfast, Mr McDonnell said he would prefer to have an election "later rather than sooner".
It comes as the government says a bill to stop a no-deal Brexit will complete its passage through the Lords on Friday.
The proposed legislation was passed by MPs on Wednesday, inflicting a defeat on Mr Johnson.
The bill says the prime minister will have until 19 October to either pass a deal in Parliament or get MPs to approve a no-deal Brexit - and after that he will have to request an extension to the UK's departure date to 31 January 2020.
In a speech later, Mr Johnson will again attack what he calls "the surrender bill" for paving the way for more "dither and delay".
Number 10 said: "He will argue that Jeremy Corbyn's surrender bill will force the prime minister to go to Brussels and surrender to any demands they make.
"This would in essence overturn the biggest democratic vote in our history - the 2016 referendum.
"The PM will not do this."
It is understood Mr Johnson will directly accuse Mr Corbyn of being "a coward".
It follows the prime minister's defeat on Wednesday over his plan to hold a snap general election on 15 October.
Labour and other opposition MPs would not back the move while the option of a no-deal Brexit on 31 October remained open to the PM.
Mr McDonnell said Labour will agree to a general election after they have ensured the legislation to protect against a no deal Brexit.
He told Radio 4's Today programme that Labour was "consulting" with other opposition parties "to determine the date" of a general election.
"The problem that we've got is that we cannot at the moment have any confidence in Boris Johnson abiding by any commitment or deal that we could construct, that's the truth of it," he said.
"So we are now consulting on whether it's better to go long therefore rather than to go short."
Liberal Democrat leader Jo Swinson said she believed Mr Johnson could try to press ahead with a no-deal Brexit, despite the legislation.
"I do have confidence that the bill will get through the House of Lords," she said.
"But in the current circumstances where we find ourselves, where we've got a prime minister seemingly prepared to do anything to rip up the traditions of Parliamentary democracy, then I also think that we need to be very aware of the risks."
Meanwhile, The Brexit Party leader Nigel Farage has warned Mr Johnson that he "cannot win an election, whenever it comes, if the Brexit Party stands against him".
However, if they were to make a pact during a general election "with a clear policy, we'd be unstoppable", he told BBC Breakfast.