London — Negotiators from the European Union and the United Kingdom agreed on a new draft Brexit deal Thursday which would, if approved by both British and European Parliaments, see the U.K. leave the EU as scheduled on October 31. If the deal is not approved, under British law, U.K. Prime Minister Boris Johnson will be forced to ask the EU for an extension to that end-of-October deadline. It was unclear Thursday whether Johnson had the support necessary to get the deal passed in Britain's Parliament.

Johnson insisted, however, that he was "confident" the deal would be approved by U.K. lawmakers.

"Now is the moment for our parliamentarians to come together and get this thing done," he told journalists.

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Britain's Parliament was scheduled to be in session on Saturday, October 19 so lawmakers could vote on the draft agreement. Parliament has only been called into session on a Saturday in Britain four times since the outbreak of World War II.

Main sticking point removed

The new deal does not include the controversial Irish "backstop," which had been a major sticking point in getting the withdrawal agreement negotiated by the EU and Britain's previous Prime Minister, Theresa May, passed by Britain's Parliament.

The "backstop" aimed to keep an open land border between Ireland (an EU member) and Northern Ireland (part of the U.K.), which has been virtually invisible — but for signs on the road — since a 1999 peace agreement ended a bloody, decades-long sectarian conflict in the region. It would have seen the entire U.K. effectively remain within the EU customs union until a more permanent solution to Irish cross-border movement could be agreed.

Hard-line "Brexiteers" refused to accept the clause, arguing that the U.K. could effectively be beholden to EU customs rules indefinitely, as another solution to the border issue might never be found, and May's proposed deal was repeatedly voted down by Britain's Parliament.

Under the draft deal announced Thursday, after Britain's exit from the European Union, Northern Ireland would remain part of the U.K.'s customs union while also remaining in the EU internal market and having customs free-trade with the EU.

"Think of Northern Ireland as the area where two circles intersect, as in a venn diagram," Professor of European and Comparative Law at Oxford University, Stefan Enchelmaier, told CBS News.

"Under the old arrangements, the entire United Kingdom kept all the arrangements as far as the customs union is concerned, and as far as the internal market is concerned, for what was foreseen as the transition period. Now… Great Britain — the island — is out of the single market and the customs union, and only Northern Ireland stays in."

A long way to go

It was unclear Thursday whether Johnson would have the votes to get his deal approved by U.K. Parliament.

Members of the Northern Irish Democratic Unionist Party (DUP) said they would not vote for the deal as it stood.

The leader of the opposition Labour party in Britain, Jeremy Corbyn, also condemned the deal and said he would back some version of a second public referendum.

"It seems the prime minister has negotiated an even worse deal than (former U.K. prime minister) Theresa May's, which was overwhelmingly rejected," Corbyn said, according the Sky News.

"The best way to get Brexit sorted is to give the people the final say in a public vote," he said.

"I have to say that I'm happy about the deal but I'm sad about Brexit," European Commission President Jean-Claude Juncker told journalists.

"If our British friends decide to return one day, our door will always be open," President of the European Council Donald Tusk said.