Labour leader Jeremy Corbyn has stepped up calls for a general election « at the earliest opportunity » to « break the deadlock » over Brexit.
In a speech, he said a new government would have a fresh mandate to negotiate a better withdrawal deal with the EU.
He told Theresa May: « If you are so confident in your deal, call that election, and let the people decide. »
The Conservatives said Labour did not have a plan for Brexit and were « playing politics ».
Labour will vote against Theresa May’s withdrawal deal on Tuesday and if, as widely expected, it is defeated, they are expected to start moves to trigger a general election.
Mr Corbyn said Labour would « table a motion of no confidence in the government at the moment we judge it to have the best chance of success ».
He added: « Clearly, Labour does not have enough MPs in parliament to win a confidence vote on its own. So members across the House should vote with us to break the deadlock. »
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Some of Mr Corbyn’s Leave-supporting backbench MPs have been speaking to Theresa May about backing her deal if she can guarantee environmental standards and rights for workers.
Others, on the anti-Brexit side of his party, are calling on him to get behind the campaign for a new EU referendum.
Mr Corbyn has said his preferred option is to trigger a general election and, having won it, seek to delay Brexit in order to negotiate a better deal with Brussels, which he says would see the UK in a permanent customs union with the EU and with a close relationship with the single market.
If Labour is not able to get a general election, Mr Corbyn said all options were « on the table, including the option of campaigning for a public vote ».
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In a speech to Labour activists at an electrical products manufacturer in Wakefield, West Yorkshire, Mr Corbyn said Theresa May would forfeit the right to govern if she cannot get her Brexit deal through the Commons.
« A government that cannot get its business through the Commons is no government at all. It has lost its mandate so must go to the country to seek another. »
Mr Corbyn vowed to heal the divide between Leave and Remain voters, saying the « real divide » in the UK was 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 ».
He said: « People across the country, whether they voted Leave or Remain, both know that the system isn’t working for them. Some see the European Union as a defence against insecurity and hostility. Others see the European Union as part of an establishment that plunged them into insecurity and hostility in the first place.
« But it’s the failed system rigged against the many to protect the interests of the few that is the real cause of inequality and insecurity, whether in Tottenham or Mansfield.
« And the real solution is to transform Britain to work in the interests of the vast majority, by challenging the entrenched power of a privileged elite.
« That is how we can help to heal the referendum’s deep divisions. »
The government has lost two Brexit votes in two days. The first defeat limits the government’s financial powers in the event of a no-deal departure. The second forces the PM to announce new plans within three days if her deal fails in the Commons.