Brexit: Which amendments MPs are voting on tonight, why Theresa May might lose - and why that could be so important

(AFP/Getty)

MPs are gearing up for a Valentine's Day clash in the latest series of Brexit votes.

Theresa May has tabled a seemingly innocuous motion asking the Commons to endorse the Brexit approach agreed last month.

However Brexit hardliners are threatening to rebel against the motion, as they believe it commits the prime minister to ruling out a no-deal Brexit.

1. What are MPs voting on?

   Government motion

   This 'neutral' motion asks MPs to welcome Ms May's statement, set out progress in Brexit talks, note that talks on the Irish backstop are "ongoing" and "reiterate its support" for the approach to negotiations agreed the last time MPs voted, on January 29.

   The problem is MPs ordered the PM to renegotiate the Irish backstop but also to rule out a no-deal exit.

   Labour frontbench (a) - Stop the government running down the clock

   Jeremy Corbyn has tabled this amendment to force the government to offer a meaningful vote by the end of February. If there is no deal, then the government has to make a statement on what the next steps will be.

   Liberal Democrats have tacked on their own amendment to this proposal, calling for a second referendum "as endorsed by the Labour Party conference".

   SNP frontbench (i) - Extend article 50

   Tabled by the SNP's Westminster leader Ian Blackford, this would require the government to negotiate an extension of at least three months to the Article 50 process.

   Pro-EU MPs (e) - Reveal secret no-deal papers

   Tory Anna Soubry and Labour's Chuka Umunna are leading calls for publication of "the most recent official briefing document relating to business and trade on the implications of a no-deal Brexit presented to cabinet.”.

   These amendments were not selected:

   Tory grandee Ken Clarke ( c ) - Allow MPs to vote on different options

   Parliamentarians will vote on a number of different scenarios, ranking them in order of preference. Any option can get on the ballot paper if more than 50 MPs back it. This idea - known as indicative votes - was mooted at the last clash.

   This proposal has the backing of senior Labour backbenchers including Harriet Harman and Jack Dromey as well as Tory Remainers Dominic Grieve and Anna Soubry.

   SNP's Angus Brendan MacNeill (d) - Revoke article 50

   Mr MacNeill, the chair of the international trade committee, has tabled this amendment to revoke article 50 before 29 March.

   Tory backbencher Sarah Wollaston (f) - Indicative votes

   This amendment by pro-EU MP Dr Wollaston demands votes on 26 February on various Brexit options including the PM's deal, no-deal, renegotiation of the backstop, a Canada-style deal, Norway-style membership of the EEA and a second referendum.

   If none commanded a majority of MPs, Ms May would have to call a second referendum with the options of her deal or Remain.

   Plaid Cymru (g) - Second referendum

   Backed by the Welsh nationalist party's four MPs, this requires the government to delay Brexit to allow for a referendum on Ms May's deal or Remain. If no extension is allowed by the EU, there would have to be a referendum at the end of the transition period in 2021 on whether the UK should rejoin the EU.

   Labour MP Geraint Davies (h) - Close alignment

   An amendment signed by a small group of Labour and Plaid MPs would require an extension of article 50 and a commitment from the PM to seek a deal - subject to ratification in a referendum - which leaves the option open for future governments to adopt Labour's current vision for post-Brexit relations with the EU, including a customs union and close alignment with the single market.

   Liberal Democrats (j) - Allow a second referendum

   Tabled by Sir Vince Cable, the party is proposing an extension to Article 50 beyond 29 March to allow time for a second referendum with remain on the ballot paper.

   Labour MP Roger Godsiff (b) - Three-option referendum

   Leave-backing Labour MP Mr Godsiff has put down an amendment for a final say vote, on Theresa May's deal, no-deal or staying in the EU.

2. Could Theresa May lose?

   The biggest threat to the prime minister is actually a defeat on the motion itself.

   Brexit hardliners are threatening to rebel as they believe it commits the prime minister to ruling out a no-deal Brexit.

   The motion asks the House to endorse the results of the recent Brexit votes. But the problem is MPs voted not only to authorise the PM to go back to Brussels and seek a replacement for the Irish backstop, but also for a non-binding motion which would rule out a no-deal outcome.

   Leave-supporting backbenchers from the European Research Group fear that this would effectively mean signing up to a bar on no-deal.

3. Why does the result matter?

   These votes are non-binding on the government but Liam Fox, the international trade secretary, warned Brexiteers that a defeat on the motion could hamper Ms May's chances of securing concessions from Brussels.

   The prime minister is trying to persuade the EU to offer legally binding changes to her deal - and senior figures are watching closely.

   If she cannot even get a neutral motion through parliament, they may be reluctant to offer concessions that could be voted down.