BRUSSELS  — British Prime Minister Theresa May launched a rescue mission for her ailing Brexit deal Friday, after the European Union rebuffed her request to sweeten the divorce agreement so she can win over hostile lawmakers at home.

EU leaders meeting in Brussels showed little appetite to resolve May's Brexit impasse for her, saying the UK Parliament must make up its mind. The choice was either back the Brexit agreement or send Britain tumbling out of the bloc in March without a deal and into unknown economic chaos.

"There is one accord, the only one possible," French President Emmanuel Macron told reporters at the end of a two-day summit. He said it was "the British parliament's time" to decide whether to accept or reject it.

The Brexit gridlock has left Britain's future looking like a high-stakes gamble with a dizzyingly wide range of possible outcomes. There could be an orderly or a disorderly Brexit. May's Conservative government could fall and an early election be held. Britain could make a last-minute request to the EU to give it more time and not leave the bloc on March 29. Some people are even pressing for the UK to hold a second referendum on Britain's EU membership.

So many possibilities, so little time.

May came to the EU summit seeking legally binding changes to the agreement, which is opposed by a majority of British lawmakers.

But the 27 other EU leaders offered only reassurances. They said they would seek to move swiftly on forging a new trade deal after Britain leaves the bloc, and promised that a legally binding insurance policy to keep the Irish border open would only be used temporarily.

They rejected British pressure to put a fixed end date on the border guarantee, and refused to re-negotiate the Brexit agreement, a 585-page legal text settling issues including the size of Britain's divorce bill and the future rights of Europeans living in Britain and Britons living in the EU. It also includes a document laying out the two sides' hopes for future relations, which isn't legally binding.

European Commission President Jean-Claude Juncker accused Britain of failing to give detailed proposals on Brexit, saying it was "up to the British government to tell us exactly what they want." May was filmed speaking sternly to Juncker as leaders arrived at Friday morning's session of the summit. She said they had had a "robust" exchange.

Nonetheless, May told reporters in Brussels that she welcomed the EU's reassuring words — and that, as formal conclusions of an EU summit, they "have legal status." "There is work still to do. And we will be holding talks in coming days about how to obtain the further assurances that the UK Parliament needs in order to be able to approve the deal," May said.

European Council President Donald Tusk, however, said no talks with Britain were scheduled.

"I have no mandate to organize any further negotiations," Tusk told reporters. "But of course, we will stay here in Brussels, and I am always at Prime Minister Theresa May's disposal." But May's against-the-odds optimism contrasted with a pessimistic tone from many on the EU side. EU leaders expressed deep doubts that May could live up to her side of their Brexit agreement and vowed to step up preparations for a potentially-catastrophic "no-deal" scenario for Britain's departure.

"We are going to be sure to prepare for all hypotheses, including the hypothesis of a 'no deal," said Belgian Prime Minister Charles Michel, who expressed a "gigantic doubt" that May could get her Brexit deal passed by British lawmakers.

But there was also sympathy for a leader who has endured the toughest week of her career.

Juncker said May was "a good friend, and I am admiring her, because this is a woman of great courage doing her job in the best way possible." May canceled a Brexit vote in the UK Parliament this week after it became clear that lawmakers would resoundingly reject the Brexit deal she concluded with the EU last month. Anger at that postponement helped trigger a no-confidence vote in May from members of her own Conservative Party. She won, but was left weakened after more than a third of her lawmakers rebelled.

Still, May insists she will secure enough changes to get Parliament's approval in a vote before Jan. 21. May says failure to support her deal could lead to a "no-deal" Brexit, which officials warn could bring economic recession, gridlock at UK ports and shortages of essential goods.

The problem is that May's deal is loathed both by pro-Brexit lawmakers, who think it keeps Britain bound too closely to the bloc, and pro-Europeans, who see it as inferior to staying in the EU.

Opposition Labour Party leader Jeremy Corbyn said the EU's refusal to renegotiate meant May's Brexit plan was "dead in the water." But Labour not yet triggered a no-confidence vote in May's government.

Many in the EU feel the problem lies with Britain's divided Parliament, which largely dislikes May's deal but doesn't agree on a better option. Luxembourg Prime Minister Xavier Bettel said the problem was not Britain's leader.

"We know what Theresa May wants, and she wants to have the possible deal passing Westminster, but the problem is the MPs in London," he said.

AP