Over the past few days, Britain has entered into a major political crisis. Negotiators for the Conservative Party government made a deal with European Union negotiators over the Brexit process. However, the deal was unacceptable to the Democratic Unionist Party, which the government relies on for support, as well as to the Labour Party and many members of the Conservative Party. Now rebel Conservatives have gathered the necessary votes to challenge the leadership of Prime Minister Theresa May. How did this happen, and what happens next?

The U.K.-E.U. exit deal was highly controversial

The key challenge that both May and the European Union face is that there is no obvious deal acceptable to both Britain and the E.U. Negotiations have been eaten up by an issue that was never seriously discussed in the lead-up to the Brexit referendum — the border between the Republic of Ireland (which remains in the E.U.) and Northern Ireland (which is part of the U.K. and, hence, is leaving the E.U.).  There are no real border controls along this frontier, which has helped cement peace in Northern Ireland, but this is threatened by the U.K.’s decision to exit the E.U. and the E.U.’s Customs Union and Single Market.

Through skilled diplomacy, the Republic of Ireland has persuaded its E.U. partners to condition a Brexit deal on a solution to the border problem. This has caused frustration among many pro-Brexit British politicians: A senior Conservative was quoted Tuesday as saying that the “Irish really should know their place.” U.K. Conservative MP Priti Patel argued that Britain should threaten to hold up food supplies to Ireland as a negotiation tactic, reviving memories of the Irish Famine in which millions of Irish starved or were forced to emigrate, in part because of negligence by the then-ruling British government.

The border issue led the U.K. and the E.U. to agree on a “backstop” arrangement, in which the entire U.K. would remain inside Europe’s customs arrangements if they could not reach a long-term deal that would solve the problem. However, the backstop has caused consternation within the Conservative Party, who see it as trapping the U.K. within E.U. rules. The obvious alternative — applying the backstop just to Northern Ireland — has been ruled out by the Democratic Unionist Party, which fears that this would bring Northern Ireland closer to the Republic, making a united Ireland (which they dread) more likely. Unionists have threatened to bring down the British government if it tries to push this through.

There isn’t any obvious alternative

The Brexit deal precipitated a crisis in British politics. May initially proposed to submit it to the British Parliament for approval. However, she had to change her mind on short notice when it became obvious that the deal was going to be voted down. There wasn’t any obvious Plan B. May has tried to get the E.U. to offer a more generous deal, embarking on a tour to persuade other E.U. leaders to either change the agreement or provide a binding legal interpretation that would water it down. It quickly became clear that the E.U. was willing to do neither. It is possible that under other circumstances, the E.U. would make concessions. However, the chaos and instability of U.K. politics means that it is at best uncertain that Britain would ratify a better deal even if it got one.

This has all been compounded by the new leadership challenge to May. Rebel Conservatives such as Jacob Rees-Mogg had tried to challenge her leadership when she came back with the initial deal but failed to gather enough support. Now they have succeeded in getting the 48 Conservative MPs they need to force a leadership contest. These rebels believe that the U.K. has already made far too many concessions to the E.U. and seem to think that a no-deal Brexit would be preferable to an arrangement in which the U.K. is still tied to E.U. rules and markets.

It’s unlikely that May will lose the leadership challenge

May appears to still have the support of a majority of Conservative MPs. She has also effectively promised to step down before the next election, turning the leadership contest into a vote over whom will lead the Brexit negotiations, with the implicit threat that leadership chaos will leave Britain worse off. However, the leadership challenge weakens May and may damage her prime ministership irrevocably if she does not win it with a large majority.

It could conceivably be that May’s weakness will provide her with an advantage in negotiations with the E.U. As Robert Putnam has argued, weakness at home may make it easier for negotiators to secure concessions abroad. These negotiators can credibly argue that they need concessions if they are to have any hope of getting the agreement approved by their skeptical domestic constituency.

However, there are also compelling reasons to suspect that, in this case, weakness at home will also be weakness in discussions with E.U. negotiators. The problem is not a home constituency that can be satisfied by specific substantial concessions. It is a hostile home constituency of Conservative euroskeptic MPs, Democratic Unionists who fear that any deal is a Trojan horse for Irish unity, and opposition parties who do not like the deal and see no reason to make the government’s  life easier. Under these conditions, there is no obvious deal that can pass through Parliament.

It is likely that any substantial concessions by the E.U. would be pocketed, leading to further demands and still further ones. Unsurprisingly, the E.U. is unwilling to reopen serious negotiations. The likely prospect is not for the chaos to be resolved easily or soon, but to continue and, perhaps, increase.