After Theresa May’s three failed attempts to win over lawmakers, current U.K. leader Boris Johnson will put his own Brexit deal to the test during a historic Saturday sitting of the British Parliament.

The House of Commons will sit from 9.30 a.m. London time “until any hour,” according to the latest agenda paper. The House is sitting on a Saturday for the first time since 1982, when the U.K. was at war with Argentina.

Aside from key changes in how Northern Ireland is treated, there appears to be little difference from May’s failed deal, but Johnson will be banking that lawmakers, tired of the Brexit deadlock, will switch to support his withdrawal deal.

Some reports suggest Johnson has persuaded hardline Brexiteers that by voting for his deal, the government can keep the threat of a no-deal on the table when trade negotiations begin during the Brexit transition period.

Johnson will make a statement at 9.30 a.m. local time, before taking at least 90 minutes of questions about his talks that led to the agreement between the U.K. and 27 other EU leaders.

In the afternoon, the government motion is expected to ask lawmakers to approve the deal. The vote is expected to be tight with more “hard Brexit” supporters in his Conservative Party now ready to back Johnson after rejecting May.

If MPs (Members of Parliament) do approve the deal unamended on Saturday, the government is expected to table the Withdrawal Agreement Bill as soon as Monday, freeing the U.K. to leave the European Union on October 31.

The U.K. then enters into a transition period until the end of 2020. During this time, the EU and U.K. would attempt to resolve future trading terms.

Should Johnson lose the vote, U.K. legislation means he has until 11 p.m. London time to send Brussels a letter requesting an extension to the Brexit deadline.

Amendments to the vote have been made possible by a Commons victory on Thursday which saw remain MPs and opponents to a no-deal Brexit vote in unison. If any amendment is selected by the Speaker of the House John Bercow and approved by lawmakers, it could mean the outcome of Saturday’s vote is altered significantly.

One possibility is a stiffening of existing legislation that prevents no deal at all, while another possible vote is on whether a second public referendum is needed to confirm Johnson’s Brexit deal.

What Johnson needs

The prime minister needs roughly 318 votes to pass the motion, but there are only 288 Conservative Party MPs.

On these calculations, which assumes all Conservatives vote for the deal, Johnson is 30 votes short.

His former reliance on 10 votes from the Democratic Unionist Party (DUP) has now evaporated with the Northern Irish party, angry at the deal struck with Europe, now vowing to oppose the government.

Further opposition can be expected from the Scottish National Party (SNP), Plaid Cymru (Welsh national party), Liberal Democrats, one Green Party MP and of course, the main rump of the opposition Labour Party.

But all is not lost for Johnson and there are three sources he can plunder for support:

Conservative rebels who the prime minister previously sacked, but haven’t yet defected to another party.

Labour lawmakers whose constituencies voted heavily to leave in the 2016 referendum.

A small number of MPs sitting as independents.

Some pro-deal Labour MPs have already confirmed they will defy their party to vote with Johnson while, conversely, some rebel Conservative lawmakers are set to reject Johnson’s proposal.

source: cnbc.com