Dominic Raab has thrown a Brexit-grenade into the leadership contest, but it may prove to have been a pretty disastrous miscalculation.

In an interview with the Spectator last week Raab indicated he would consider suspending parliament to force through a no deal Brexit. And at last night’s One Nation conservative hustings he doubled down, and all but confirmed he would pursue that tactic in the event MPs try to block no deal – an almost inevitable scenario.

Andrea Leadsom, Sajid Javid and Boris Johnson – all committed Brexiteers – ruled out proroguing parliament last night. So with this move Raab has positioned himself as the hard Brexiteer’s most robust Brexiteer. As Boris storms ahead in the polls, and continues to receive endorsements from all corners of the Conservative party, Raab has hammered home his Brexit credentials to win over the ERG, hardline Brexit wing of the party.

Proroguing parliament would amount to Dominic Raab (as prime minister) ending a parliamentary sitting, sending MPs away from Westminster until the UK leaves the EU, denying them the opportunity to try to block a no deal Brexit. It’s an extreme measure, largely because it implicates the Queen in a bit of a constitutional controversy.

Another leadership hopeful, erstwhile Remainer and staunch anti-no dealer Rory Stewart has said “it would be illegal… it would be unconstitutional and it would be undemocratic.” Amber Rudd has added that it would be “outrageous” and Speaker John Bercow has entirely ruled it out, saying: “that’s simply not going to happen. It’s so blindingly obvious.” So, the moderates and Remainer wing of the party aren’t impressed. But committed hard-Brexiteer Dominic Raab – who resigned over May’s Withdrawal Agreement – was never going to win over those votes anyway. He’s angling for an entirely different group.

Raab is trying to prove he has a plan. While all candidates across the no deal vs deal spectrum are waxing lyrical about how they would get Brexit done, all have failed to put forward a legitimate proposal that doesn’t see them in the exact same position that May found herself in. Parliament will block no deal, they will probably block revocation too. There’s no majority for May’s deal and there doesn’t appear to be any other deal on the table. Matt Hancock’s grand proposal still involved time-limiting the backstop, something it appears the EU will never do. There’s been a lot of talk about alternative arrangements too – but what those alternatives are is up in the air. Raab has come in with a clear plan to get Brexit over the line.

Except the caveat is this: coming forward with a plan only works if the plan is workable. It only works if it’s a plan that won’t lose him the support of vast swathes of the party – seeing that support move over towards his main rival Boris. And it only works if it doesn’t involve putting the Queen in a bind. The Stop Boris brigade have pretty rapidly turned their attention to the Stop Raab cause.

Will Raab’s pitch work? He wants to win over the ERG votes – but as ever the ERG is divided. They haven’t chosen a candidate to back as a bloc, and as a result their vote is split. Andrew Bridgen has backed Boris. Suella Braverman has gone for Raab. Some will go for outsiders Esther McVey and Andrea Leadsom. And if Steve Baker declares we can certainly expect him to get the support of the true Brexit fringers like Mark Francois.

If Raab could count on the ERG acting in their best interests and as a coherent bloc – putting all their votes behind one candidate – then this approach may have worked. But anyone who has observed the ERG throughout the Brexit process would know never to count on such unified decision making.

However, there is a second calculation that may work in Raab’s favour. While Raab is not the only hardline Brexiteer running (with McVey, Leadsom, and possibly Baker running), he’s certainly their frontrunner. When they inevitably drop out of the race where do their votes go? The calculation Raab will surely make is that those initial votes will then transfer to him in the second round. If he’s right then we might see Raab on the final ballot. But, the hard Brexit vote in parliament is split. Some of their votes will inevitably go to Boris, and he looks set to run away with the whole thing.

Boris is storming ahead with endorsements. And benefiting from the credibility gap of his rivals – people back him because they believe he can win. Not only that, but he’s captured large swathes of the hard Brexit vote – thanks to setting the parameters of the debate early on by saying the UK will leave the EU on 31st October “deal or no deal.” And, with the backing of Cameron’s former deputy chief of staff Oliver Dowden Boris is also capturing parts of the one nation conservative Cameroon vote. Then there are the up and comers, like Rishi Sumak, whose endorsements are also crucial.

Boris has managed to appeal to all corners of the party, while Raab’s proroguing tactic will alienate even some Brexiteers.

It remains Boris’s contest to lose.