Mr Corbyn has twice Prime Minister Boris Johnson's calls for a snap poll, insisting that a no-deal Brexit must be off the table first.
Comparing no deal to the 2008 financial crash that saw "tens of millions of people who had nothing to do with it" pay for the consequences, Corbyn will warn that the government would seize the opportunity to "push through policies that benefit them and their super-rich supporters".
However, Mr Watson will argue it is not too late for Labour to win back Remain voters put off by confusion over the party's position on Brexit, if they were to commit clearly to campaign to stay in the EU.
The 70-year-old said an incoming Labour government would hold a new referendum - with Remain and a "credible" option for Leave on the ballot paper.More news: Paul Pogba price set at £179m for Real Madrid
Addressing the annual Trades Union Congress conference, Mr Corbyn said he would reverse the "deliberate, decades-long transfer of power away from working people". So a general election is coming.
Senior Labour figures had been arguing that backing Remain would recover ground lost to the pro-EU parties such as Plaid Cymru and the Liberal Democrats in recent elections.
Ordering the Prime Minister to seek a further extension to Article 50 is a gift to Boris Johnson's bid to present himself as the champion of the biggest democratic vote in British history who has to face off a Parliament determined to thwart the people's will. Labour are running scared of an election and only offer more dither and pointless delay.
"The only way to break the Brexit deadlock once and for all is a public vote in a referendum", he will say. "Just as we worked throughout the summer to pass a law preventing no deal, so we will work each and every day we are shut down to enforce that law".More news: Green Day, Fall Out Boy and Weezer to hit Hard Rock Stadium
Corbyn also stressed Labour's plan to give workers a third of seats on company boards, and pledged to create a Workers Protection Agency to enforce rights, standards and protections at work and introduce sectoral collective bargaining to set industry-wide minimum standards.
He will also blast no-deal as a "Trump deal Brexit", adding: "It will put us at the mercy of Trump and the big United States corporations itching to get their teeth further into our NHS, sound the death knell for our steel industry, and permanently drive down rights and protections for workers".
"Prime minister: you can hide from parliament for a few weeks, but when we return we will be ready", Starmer will say. "Once we get out of here, there isn't any way to establishment-up Jeremy", one Labour source said.
The PM had already kicked off his unofficial election campaign with a visit to Yorkshire on Thursday, during which he re-announced his police recruitment drive.More news: The United States of America wins The 47th Walker Cup match
On a general election, Sir Keir will say: "We have to stop no-deal".