LONDON (Reuters) – British Prime Minister Theresa May on Thursday urged lawmakers to back her agreement to leave the European Union, but made little headway with a bid to coax rebellious members of her party into supporting her deal.

May has repeatedly warned that if lawmakers reject her deal with Brussels, which would see Britain exit the EU on March 29 with continued close ties, the only alternatives are leaving without a deal or reversing Brexit.

The British parliament is mid-way through a five-day debate on the Brexit deal, ahead of a crunch vote on Dec. 11 which will define Britain’s departure from the EU and could determine May’s own future as leader. She currently looks set to lose that vote.

The day before the vote, on Dec. 10, the European Court of Justice of Justice will deliver a judgment on whether Britain can unilaterally reverse its move to leave.

“There are three options: one is to leave the European Union with a deal … the other two are that we leave without a deal or that we have no Brexit at all,” May told BBC radio.

May said she was speaking to lawmakers about giving parliament a bigger role in whether to trigger a so-called Northern Irish backstop arrangement or extend a transition period during which more EU membership terms would apply.

CHARM OFFENSIVE?

Concerns about the backstop are a key driver of opposition to the deal among both May’s own Conservative lawmakers and the Northern Irish Democratic Unionist Party (DUP), which props up her minority government.

Supporters of a clean break with the EU say the backstop, intended to ensure no hard border between British-ruled Northern Ireland and the EU-member Irish Republic, could leave Britain forced to accept EU regulations indefinitely, or Northern Ireland treated differently from the rest of Britain.

“There are questions about how decisions are taken as to whether we go into the backstop, because that isn’t an automatic,” she said. “The question is: do we go into the backstop? Do we extend … the implementation period?”

On Wednesday, May’s top parliamentary enforcer, or chief whip, Julian Smith, spent an hour meeting with pro-Brexit Conservative and DUP lawmakers, listening to their concerns about the deal. But lawmakers who attended the meeting said he did not offer a solution to persuade them to back it.

“This was not about doing deals, it was about listening,” said one leading pro-Brexit lawmaker. Another said it was: “Too little, too late.”

May’s minority government governs with a working majority of 13 thanks to its deal with the 10 DUP lawmakers.

The DUP says it will vote against the deal but would support May in a vote of confidence if the deal fails.

During the first two days of debate, 15 of May’s own lawmakers have explicitly said they intend to vote against it. She will either need to win them back or win over a substantial number of opposition lawmakers, which appears unlikely.