Jeremy Corbyn is to reiterate his call for the Brexit impasse to be put to the people in a general election, as Labour edged closer to pledging to call a no-confidence vote in Theresa May’s government if her departure plan is voted down in the Commons.

At a speech in Wakefield on Thursday, the Labour leader is to argue that if May is unable to get her flagship piece of legislation past MPs next week then her government will have lost all authority, meaning an election is urgently needed.

“So I say to Theresa May: if you are so confident in your deal, call that election, and let the people decide,” he will say, according to extracts from the speech released in advance.

“To break the deadlock an election is not only the most practical option, it is also the most democratic option. It would give the winning party a renewed mandate to negotiate a better deal for Britain and secure support for it in parliament and across the country.”

Labour’s policy on Brexit is to first of all seek a general election, and only if that does not happen to consider the idea of a second referendum, a stance which has prompted some pressure from a membership predominantly keener on another referendum.

The party has also avoided specifics on when it might push for an election, something it could force under the Fixed-term Parliaments Act by winning a specifically worded motion of no confidence in the government.

On Wednesday, two of Corbyn’s frontbenchers indicated this moment could come very soon after what Labour hopes will be defeat for the government when the delayed vote on May’s Brexit deal finally happens next Tuesday.

Barry Gardiner, the shadow international trade secretary, told BBC Radio 4’s Today programme: “Obviously, the next thing to do immediately after that is for there to be a vote of confidence in the government.”

Speaking later on Sky News, Andrew Gwynne, the shadow communities secretary, confirmed the plan. Asked if this meant a confidence vote would come “next week, basically” if May lost the vote. Gwynne replied: “Absolutely.”

According to the extracts of his speech, Corbyn will say Labour will vote against the “bad deal” proposed by the prime minister.

“If the government cannot pass its most important legislation, then there must be a general election at the earliest opportunity,” he will say. “A government that cannot get its business through the House of Commons is no government at all.”

On the wider issue of national divisions, Corbyn is to argue that Brexit is more of a symbol than a cause of splits. “The real divide in our country is not between those who voted to remain in the EU and those who voted to leave. It is between the many, who do the work, create the wealth and pay taxes, and the few, who set the rules, reap the rewards and so often dodge taxes.

“If you’re living in Tottenham, you may well have voted to remain. You’ve got high bills, rising debts, you’re in insecure work, you struggle to make your wages stretch, and you may be on universal credit and accessing food banks. You’re up against it.

“If you’re living in Mansfield, you are likely to have voted to leave. You’ve got high bills, rising debts, you’re in insecure work, you struggle to make your wages stretch, and you may be on universal credit and accessing food banks. You’re up against it.”

While some people saw the EU as “part of an establishment that plunged them into insecurity and hostility”, the real issue was a wider system which entrenched the power of an elite, he will say.

During the first prime minister’s questions of 2019 on Wednesday, Corbyn mocked May over what he said was her failure to get any further assurances from EU leaders to placate Tory MPs or her Democratic Unionist party partners since pulling the vote planned for December.

“Isn’t the PM bringing back exactly the same deal she admitted would be defeated four weeks ago?” he asked, saying the prime minister was offering only “window dressing”.

Twice he asked May if she would discount the idea of no deal, especially after MPs backed an amendment to the finance bill from Labour’s Yvette Cooper to curb some of the government’s tax administration powers in the event of the UK crashing out of the EU.

May responded by saying Corbyn was himself ruling out the only deal acceptable to Brussels. “The only way to avoid no deal is to vote for the deal,” she said.