Theresa May could lose Tuesday’s meaningful vote on her Brexit deal by a margin of more than 200 votes if all the Conservative MPs who have indicated that they will vote against her pact stick to their word.
An FT analysis of MPs’ voting intentions establishes that, in a worst-case scenario, Mrs May could lose by a 225-vote margin — which would break all records for a Commons division in the last 100 years.
The FT tally suggests that, under such a scenario, 198 MPs would vote for the motion and 423 against (it excludes 17 MPs whose position was ambiguous).
The analysis was drawn up by examining MPs’ statements on Mrs May’s pact in media interviews, social media posts and parliamentary debates.
If the tally is narrowed to include only the MPs who have made the most categoric statements — which yields the highest level of confidence — Mrs May would be behind by 228 votes to 129, with much of the Commons yet to make up its mind.
But the worst-case figure is in line with private comments from one former Tory cabinet minister who said last week: “She’ll lose by more than 200.”
Government insiders still hope the PM’s deal can be revived if the margin of defeat is contained to a much lower level — around 50 to 80 — as MPs change their minds.
Much depends on whether Tory MPs back amendments to the meaningful vote that could rally the support of Brexiters for the prime minister’s deal by demanding further concessions from Brussels.
Since Mrs May struck her deal in November, at least 79 Conservative MPs have indicated they will vote against her Brexit deal. A further 33 Tories have made more equivocal comments about their opposition to the deal. That makes a total of 112 Tory MPs who could go into the No lobby.
The latest addition to the list of rebels is Gareth Johnson, who resigned as a Conservative whip on Monday to oppose the deal.
“Unfortunately this agreement prevents us taking back control and instead could leave us perpetually constrained by the European Union,” he wrote in a letter to the prime minister.
The Tory pro-Brexit rebels would probably be supported by the Democratic Unionist party’s 10 MPs who are also likely to hold fast in their opposition to the deal.
By contrast, at least 128 Conservative MPs have stated that they would support the prime minister. This includes four former critics of the deal — Geoffrey Clifton-Brown, Caroline Johnson, Edward Leigh and Andrew Murrison — who reversed their position over the weekend.
A further 63 Conservative MPs have made statements suggesting they are likely to back Mrs May, and 13 have made no clear statement either way.
But even if all these MPs fall into line behind Mrs May, the government would remain well short of a majority.
Mrs May would need large-scale defections from opposition MPs to overcome the rebellion in her own ranks. But Labour has been far more united than the Conservatives, with only five of the party’s 229 MPs making suggestions they could break with the party to support the prime minister.
Among Labour MPs, Kevin Barron made the clearest statement that he would defy his party’s whip and vote with the prime minister.
“It is the only option that fulfils the promises I made to my constituents in Rother Valley and avoids the horror of a no-deal Brexit,” Mr Barron wrote on Twitter.
Two other opposition MPs — independent Unionist Sylvia Hermon and Stephen Lloyd, who resigned the Liberal Democrat whip over the issue — are also supportive of the deal.
Where no unequivocal public statement on their voting intention exists, MPs were assigned to the lower-confidence categories based on their positions within the party and their previous statements on Brexit.
With Sinn Fein’s seven MPs not seated and the Speaker and his three deputies not voting, 319 votes are needed for a majority in the House of Commons.
Additional reporting by David Blood, Aleksandra Wisniewska and Max Harlow. Graphics by Chris Campbell and John Burn-Murdoch.
Get alerts on Brexit when a new story is published