Update: Alex Wickham, Buzzfeed's Brexit reporter, reported on Monday that a handfulof Tory MPs who had previously backed an amendment calling for a customs union are now turning against it in favor of supporting Johnson's deal with the EU.

NEW: Tory MPs Who Previously Backed A Customs Union Are Now Shifting Against It



Damian Green and Paul Masterton tell BuzzFeed News they will now vote against CU amendment



Victoria Prentis tells @KateEMcCann she's also switched againsthttps://t.co/kH5blgbYQx — Alex Wickham (@alexwickham) October 21, 2019

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After MPs voted on Saturday to delay a vote on Boris Johnson's Brexit deal, forcing Johnson to ask the EU for another delay, the PM is preparing to try again on Monday and put the deal to another vote in the House of Commons in an attempt to win lawmakers’ support for the deal he struck with the EU, Bloomberg reports.

The pound rallied on Monday, breaking above $1.30, amid growing optimism that Johnson had enough support to push his agreement through the Commons. The currency has struggled to break above $1.30, leaving it vulnerable to a selloff.

Johnson’s plan to hold a second vote could founder should Commons Speaker John Bercow decide to rule against the PM and claim the vote cannot go forward due to procedural rules. The speaker, who is preparing to leave his position in the not-too-distant future, could decide not to allow the vote because it amounts to asking the Commons to vote on the same question twice in the same session, in violation of parliamentary rules (the arcane rules of the UK's parliament have played an important role so far during the Brexit process).

The government announced early on Monday that it would move ahead with the second vote so long as Bercow permitted it, and so long as amendments weren't attached to the bill to render it meaningless. If MPs vote for an amendment calling for the UK to remain in the EU customs union, the government will also pull the vote.

In one possible explanation for holding the vote so soon, the cabinet said it now has the backing of the 320 MPs needed to win a vote on approving Johnson’s Brexit deal.

Brexit latest:

- No10 will pull today's meaningful vote if Bercow allows any amendments

- Govt likely to scrap attempt to get Brexit deal through Parliament if MPs vote for customs union amendment tomorrow

- General election could then follow by end of Nov — Gordon Rayner (@gordonrayner) October 21, 2019

Johnson received a boost when former cabinet minister Amber Rudd, who left the government and the Tory party in protest at the expulsion of 21 colleagues last month. She said that many of those who were expelled from the Tories ranks were ready to cooperate with the PM.

The PM also has the backing of a small number of Labour MPs, though it might be difficult for him to win over too many more.

Meanwhile, the DUP’s 10 votes made the difference between defeat and victory for Johnson on Saturday, and there's no indication that the party is softening in its position.