U.K. Prime Minister Theresa May is calling off a crucial vote in Parliament on whether to approve her Brexit deal and will head back to Brussels to seek a better offer from the European Union.

May told her Cabinet she will travel to Brussels for talks with EU leaders on Thursday and ask for better terms on the most controversial part of the withdrawal agreement — the plan for the Irish border. She spoke to leaders by phone at the weekend, though the bloc has made clear it won’t re-open negotiations.

The vote in the House of Commons was due to be held on Tuesday evening but is now set to be rescheduled, according to people familiar with the situation.

The pound fell to the lowest since June 2017 as fears about a no-deal Brexit resurfaced. U.K. Government bonds rallied, with yields hitting the lowest since August.

May’s plan to delay the vote throws the Brexit process into further turmoil. She has promised to give the House of Commons a binding say on whether or not to ratify the U.K.’s withdrawal agreement with the EU before the country leaves the bloc on March 29. It’s now unclear when that vote will happen, though some expect it won’t be called until January.

The stakes for May are high. If Parliament refuses to endorse the withdrawal agreement, the U.K. will be on course to leave the EU without a deal, unleashing political and economic chaos. May herself could be forced from office and the U.K. might need a fresh election or referendum to resolve the crisis.

The prime minister spent the weekend talking to fellow EU leaders to update them on her struggle for support and to explore possible changes to the agreement to make it more palatable. She will attend an EU summit on Thursday.

The political situation in London is volatile. Facing the threat of plots to oust her, May will make a statement to Parliament on Brexit on Monday afternoon when she is expected to confirm her plan to shelve the vote and set out the reasons why.

She’s battling to quell a revolt from pro- and anti-Brexit politicians inside her own Conservative Party, with dozens of rebels trying to force her out as party leader and prime minister. Separately, the opposition Labour Party is weighing up whether to call a formal vote of no confidence in the government. If May loses that, the U.K. would be on course for an election.

“This is essentially a defeat of the prime minister’s Brexit deal” and shows the terms of the divorce were so bad that May didn’t even dare to put it to a vote, leading pro-Brexit Conservative Steve Baker said. “This isn’t the mark of a stable government or a strong plan.”

“We don’t have a functioning government,” Labour Leader Jeremy Corbyn said. “While Theresa May continues to botch Brexit, our public services are at breaking point and our communities suffer from dire under-investment.”

May’s office publicly insisted the vote was going ahead as recently as 11:20 a.m. on Monday in London but the prospect of an overwhelming revolt from members of Parliament forced the premier to think again. She informed her Cabinet of the decision during a conference call which started at 11.30 a.m.

Graham Brady, chairman of the 1922 Committee representing rank-and-file Tory lawmakers, said May’s decision to pull the vote “is clearly the right thing to do.” He is a key figure because he receives the letters from lawmakers that could initiate a leadership challenge in May.

Last week Brady had publicly urged the premier to drop her plans for a vote, amid opposition to the so-called Irish border backstop. In an interview Monday, he said, “Obviously there wasn’t sufficient support to press ahead successfully.”

“Everyone knows what the bone of contention is — the backstop — and there are a large number of MPs who are prepared to compromise,” Brady said. Now the prime minister can go to Brussels and re-negotiate, he added.

Delaying the vote is likely only to provide a temporary reprieve for the premier as she has promised to give Parliament a decisive say on whether to accept or reject the agreement before the U.K. leaves the bloc on March 29.

“Pulling the ‘deal’ vote would just delay the inevitable,” Tory MP Philip Lee tweeted. “Brussels will not grant any further significant concessions.”