Boris Johnson is still pursuing today's vote as a decisive moment for the Brexit deal, rather than the start of yet another delay, with the Letwin amendment meaning the real meaningful vote could be moved to Tuesday. His opponents are speaking in a similar vein, framing the choice facing those MPs yet to make up their minds as being one concerning how trustworthy the Prime Minister is.
Perhaps the most powerful argument against trusting Johnson came from DUP Westminster leader Nigel Dodds, who told the Chamber that: 'It was once said that no British prime minister could ever agree to such terms and indeed those who sought the leadership of the Tory party said so at our conference'. This has been joyfully picked up by Labour MPs who are trying to lean on their colleagues not to back the bill. Sir Keir Starmer told the Commons that those who are considering putting their trust in Johnson should reflect on Dodds' point, adding: 'I ask how anybody can trust any promise he is now making.'
This matter of trust is a serious consideration for the wavering MPs. Firstly, do they believe Johnson when he reassures the Commons that there will be no scaling back of workers' rights as a result of the removal of the level playing field with the EU? Secondly, do they believe his assertion that there isn't a border down the Irish Sea and there will be a single united customs union when the DUP is insisting the opposite? And what about the line from John Baron, that he was happy to support the deal because it could mean Britain might leave on WTO terms? Baron is irritably intervening on MPs who keep bringing this quote up, saying they are wilfully misunderstanding him and that he does want a free trade agreement with the EU.
Then there are the personal matters: MPs often wrangle benefits for their constituencies out of a prime minister when approaching votes like this, and have to work out whether commitments really can be delivered by a government which may be about to go to the polls. Ex-Tory MPs are being promised that voting for the deal today will put them 'on track' to returning to the party fold.
But it's not just about whether MPs trust the Prime Minister. Those considering whether to support the Letwin amendment are also having to work out whether they really trust the others backing it. Letwin insists that he does want Britain to leave on 31 October. But that's not the case for a lot of other MPs, who see his plan as a way of spinning Brexit out further, hopefully to the point that they can get their way on a second referendum, which they hope will mean Britain doesn't leave at all. That's one of the reasons some of the ex-Tory MPs aren't going to support Letwin: they are anxious that it is time to get Brexit done, and that to support even a well-meaning amendment will mean that they further damage public trust in politicians.
Though the Letwin amendment means today may not be the day when parliament decides whether to back the Brexit deal, it is the day when MPs have to decide who they trust the most about what is going to happen next.