British MPs will vote on Wednesday (4 September) whether to delay Brexit once again, but the government aims to call an election to stop them.

The motion up for Wednesday's vote says Britain should ask the EU to postpone Brexit day from 31 October to 31 January 2020, unless MPs back a new withdrawal deal or a no-deal exit before the end of October.

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The new vote comes after opposition MPs together with 21 rebels from the ruling Conservative party defeated prime minister Boris Johnson's plan to stop parliament having a say on Brexit, by 328 votes to 321 on Tuesday evening.

Johnson reacted by promising to call an election on 15 October in the hope of winning a popular mandate to leave on 31 October no matter what.

He also punished his rebels, which included senior figures such as former finance minister Philip Hammond and former law lord David Gauke, by expelling them from the Tory party.

The prime minister said he would "never" ask the EU for another delay because that would "hand control of the negotiations to the EU".

"The people of this country will have to choose," he said.

Conservative peers in the House of Lords also pledged to table scores of amendments to the Brexit delay motion in order to filibuster its final adoption.

But opposition leader Jeremy Corbyn said parliament would fight Johnson on his snap election call, which requires a two-thirds majority, unless the Brexit delay bill was passed first.

"Get the bill through first in order to take no-deal off the table," Corbyn said.

Some Tory rebels later went on air to criticise Johnson's handling of the situation.

The party had "been taken over by a rather knockabout sort of character [Johnson], who's got this bizarre crash-it-through philosophy ... a cabinet which is the most rightwing cabinet any Conservative party has ever produced," Ken Clarke, who had been a Tory MP until Tuesday, told the BBC.

But Johnson loyalists are calling the delay motion a "shameful document" that could cause a "permanent cancellation of Brexit".

Johnson will be back in parliament at noon for his first-ever prime minister's questions ahead of the voting.

His finance minister, Sajid Javid, will, the same day, reveal a new budget for 2020-2021.

The government had earlier promised to spend £6.2bn [€6.8bn] to cushion the blow of a no-deal exit.

But a new report by Unctad, the UN's trade agency, out on Tuesday said a crash-out would cost the UK $16bn [€15bn] in lost EU sales due to higher tariffs alone.

And it added that "these losses would be much greater because of non-tariff measures, border controls, and consequent disruption of existing UK-EU production networks".

For its part, the EU aims to unveil its no-deal emergency plans in Brussels also on Wednesday.

These are to include payments from the European Solidarity Fund, normally reserved for natural disasters, and from the European Globalisation Adjustment Fund, according to a document seen by the Reuters news agency.

They will also include "flexible solutions" on letting EU countries pay out state aid to stricken companies.

Irish reaction

The Irish finance minister Paschal Donohoe indicated on Tuesday that the EU might not accept a new 31 January deadline and might push for a longer extension instead.

"The European Council and the European Commission have said that were another extension to be looked for, there would have to be a very significant political rationale for it and it is yet to be seen what that rationale would be," he told Irish broadcaster RTE.

The US vice-president, Mike Pence, who was in Dublin at the time, said he was "confident that if both parties [the EU and UK] will come to the table and negotiate in good faith we truly believe that by the end of October a deadline can be met with Brexit".

Johnson is due to meet Irish leader Leo Varadkar next week to discuss ways to keep open the Irish border while ditching EU customs rules - the main sticking point in previous Brexit agreements.

But Varadkar quashed the idea that he might do a side-deal with Johnson, bypassing EU concerns.

"We don't negotiate bilaterally," Varadkar said.