May was supposed to have come up with a credible alternative Brexit plan, that could be passed by her Parliament, to present at the summit in Brussels, yet talks with the UK opposition Labour Party on that new deal have failed to bear fruit.It’s likely, then, that the summit will be difficult, but not a disaster for May. And yet even if she squeaks through it unscathed, the storm clouds are gathering back home. Those talks with the Labour leader Jeremy Corbyn and his allies are not just about window dressing, but a serious attempt by both parties to reach a consensus on Brexit. But they are in danger of coming to nothing because both sides remain far apart on issues like a permanent customs union between the UK and EU after Brexit. The talks are scheduled to resume Thursday, but there is a sense in Westminster that because both parties remain far apart on the fundamentals the two sides are just going through the motions. This sense is being picked up in Europe too, which is why EU leaders are pressing for a long delay to Brexit — of up to a year — because there is no quick deal in sight.Party splitOf more urgent concern to May will be the mood of her Conservative Party. There was a point, a week or so ago, when despite crushing parliamentary defeats on the prime minister’s original Brexit deal, Conservative Eurosceptic lawmakers were starting to weaken their opposition to May’s plan — in the interest of making sure Brexit happens and stopping Corbyn becoming prime minister. Yet May’s decision to open up talks with the Labour leader have caused outrage inside her own government, ordinary Conservative lawmakers and grassroots activists. Now, the prospect of the EU imposing a lengthy delay to Brexit has only compounded that outrage. Conservative lawmakers are starting to get restless, once again, about May’s ability to cling to power.An ominous sign of this restlessness for the prime minister appeared in the House of Commons Tuesday, when more than half of Conservative members failed to support May on what should have been a straightforward vote to approve the PM’s request for a short extension to Brexit until June 30. As May traveled to Berlin and Paris to appeal for support from German Chancellor Angela Merkel and French President Emmanuel Macron, 97 Conservative lawmakers voted against the short delay, and a further 80, including some ministers, abstained. The measure passed thanks to Labour support. While May is protected from a vote of no confidence in her leadership by her own party until December — due to an official year-long period of grace following an unsuccessful bid to unseat her last Christmas — this is not stopping some Conservative Brexiteers from wanting her to renew their attempts to get rid of her and replace her with a tougher leader and prime minister who would be happy for the UK to leave the EU without a deal. May to step down?Last month, May signaled her intention to step down once Brexit takes place. This position is too vague for the most rebellious of her own MPs. What’s more, May has already made clear she should not stay on as leader if Brexit slips beyond a June 30 timetable. If EU leaders press for that longer delay, to the end of December or even March next year, the pressure on May to stand down will be immense.First, she must get through this week’s summit. European Council president Donald Tusk, and a majority of EU leaders, are happy to give the UK its “flextension” — a flexible extension period which could be shortened if the Commons finally passes a deal. A draft conclusion for EU leaders to back, circulated last night, states that the UK must act in a “constructive and responsible manner” during the delay period — in an attempt to prevent a more hardline future prime minister cutting up rough over Brexit.But French President Macron is driving a harder bargain, insisting on tougher rules for the UK, including a review of its progress towards a Brexit deal every three months and relegating its membership status to “intermediate,” with few rights or influence. May has a weak hand going into Wednesday’s summit — but every day longer the UK stays in the EU, the more unstable her position becomes back home.