Procedurally, the UK has three options:

1. Ratify the Withdrawal Agreement (with possible accompanying changes to the Political Declaration on the future relationship with the EU) before 22 May, and cancel participation in the European Parliament elections
2. Ratify the Withdrawal Agreement (with possible accompanying changes to the Political Declaration on the future relationship with the EU) before 30 June, and ensure that when the new European Parliament session opens on 2 July, there are no UK members of the European Parliament (MEPs)
3. Take longer over the process, accepting that the UK will elect MEPs who will take their seats in the European Parliament, and run toward the 31 October deadline agreed with the European Council

The only realistic route to either of the first two outcomes lies in the talks between the government and the Labour Party (Labour). Like the government, Labour can accept the Withdrawal Agreement – and the debate between them is over the future relationship and how any agreement would bind a (potentially more pro-Brexit) successor to the Prime Minister.

The central issue in the talks is future customs arrangements (Labour has argued for participation in a Customs Union), but the possibility of a confirmatory public vote (the Labour leadership is split on this, but it is strongly supported by many Labour members of Parliament [MPs] and party members) looms in the background. In Parliament, on 11 April, the Prime Minister indicated that, rather than seeking another “meaningful vote” on the withdrawal package, the government might bring the result of any talks with Labour back to the House of Commons by trying to pass the Withdrawal Act, the implementing legislation, which gives effect to the provisions of the Withdrawal Agreement. Passage of the Withdrawal Act would be enough to enable the UK to ratify the Withdrawal Agreement without having to hold a further “meaningful vote”.

In the event that the government cannot reach agreement on a way forward with Labour, it will seek agreement with Labour on a procedure to put a limited number of options back to Parliament to try to reach agreement on one of them, which the government will try to agree with Labour that both should then support through its passage through Parliament. Labour has not yet committed to this.

The government will hope that the prospect of the UK having to participate in European Parliament elections nearly three years after voting to leave the EU will concentrate MPs’ minds. Certainly, the Conservative Party is in a state of disarray and anger, and the Eurosceptic strand of British politics is mobilising: Nigel Farage (MP) has started a new Brexit Party, which appears to be polling well, and his old UK Independence Party (UKIP) (whose support has collapsed since the referendum) would see it as a chance to relaunch themselves. On the other side of the argument, pro-European parties (e.g. the Liberal Democrats, Scottish and Welsh nationalists, and the new Change UK) will hope that they can mobilise the up to 1 million who marched in London last month, and the 6 million or so who have signed the Revoke petition online. Of the two major parties, initial polling suggests that the Conservatives stand to do badly, damaged by incumbency, by the messiness of Brexit, and by the Brexit Party/UKIP on one side, and (probably to a more limited extent) Change UK and the pro-European parties on the other. Labour, however, does not look to be so negatively affected. On both sides of the debate, European parliamentary elections are likely to be seen as a proxy for the current state of public opinion. The incentive to avoid this is strongest for the Conservative Party.

If the government does not succeed in agreeing a way forward with Labour, which delivers Brexit in May or June, wider political options may open. The Prime Minister looks determined to carry on, and cannot formally be challenged in the Conservative MPs’ confidence vote until December, but the pressure on her to stand down will grow. The results of the elections will be seen as an indicator of the current state of pro-Brexit and pro-European opinion – recent polling suggests a hardening of “no-deal” Brexit opinion, but also a drift in the overall position towards Remain. The “confidence and supply” agreement between the Conservatives and Northern Ireland’s Democratic Unionist Party (DUP), which gives the government its slim parliamentary majority, is up for renewal in June. A General Election would be a possibility within the 31 October deadline, particularly if there is a new Conservative leader (and Prime Minister), but neither major party really wants one. A second public vote/confirmatory vote is creeping up in likeliness in these circumstances, but while the decision to hold one could be taken before 31 October, the vote itself would take longer and require a further extension to the Article 50 deadline.

Meanwhile, the UK government has formally halted its “no-deal” Brexit preparation, and stood down the 6,000 officials involved.