LONDON — After an embarrassing setback in Parliament, Prime Minister Theresa May was touring European capitals on Tuesday, meeting with leaders and looking for some way to shore up support back home for her agreement on Britain’s withdrawal from the European Union.
British lawmakers had been scheduled to vote on the agreement on Tuesday, but after a debate in which it came under attack not only from the opposition but also from many members of her own Conservative Party, Mrs. May delayed the vote on Monday, acknowledging that her plans had faced defeat “by a significant margin.”
Her retreat undermined the tenuous hold on power by a prime minister whose opponents, both inside and outside her party, have been speaking openly about trying to topple her. It also left Britain’s exit from the European Union, or Brexit, in limbo, with lawmakers and analysts alike saying it was anyone’s guess what would happen next.
On Tuesday afternoon, Parliament is to hold an emergency debate on the postponement of the vote, called by Jeremy Corbyn, leader of the opposition Labour Party — essentially a chance for lawmakers to vent their discontent.
Parliament will get a chance to vote on the agreement some time before Jan. 21, a spokesman for Mrs. May told reporters on Tuesday. There had been speculation that a vote could technically be delayed until March, when Britain is scheduled to leave the union.
The prime minister met Tuesday morning in The Hague with her Dutch counterpart, Mark Rutte, who is seen as her closest ally within the European Union, and then flew to Berlin to meet with Chancellor Angela Merkel. Later in the day, she planned to travel to Brussels to meet with European Union leaders. The union’s heads of government are to meet on Thursday and Friday.
Ahead of those meetings, European Union officials insisted that there could be no changes to the text of the agreement reached last month between the bloc and Mrs. May’s government, after nearly two years of negotiation.
“The deal we have achieved is the best deal possible, it is the only possible deal,” Jean-Claude Juncker, president of the European Commission, told a meeting of the European Parliament on Tuesday morning. “There is no room whatsoever for renegotiation. But of course, there is room, if used intelligently, there is room enough to give further clarification and further interpretations without opening the withdrawal agreement. This will not happen. Everyone has to note that the withdrawal agreement will not be reopened.”
Antonio Tajani, president of the European Parliament, said to Mr. Juncker: “The Parliament is exactly in line with you when it comes to Brexit. We won’t be changing a position which has now been adopted.”
European Union officials voiced frustration and impatience with the paralysis in London. Mr. Juncker described Brexit, which he and other officials had hoped was a settled matter, as “a surprise guest” at the summit meeting this week, and not a welcome one.
In Parliament on Monday, Mrs. May spoke of seeking assurances from European Union leaders about the deal, particularly on the status of Northern Ireland, but she dodged repeated questions from other lawmakers about whether she would try to alter the agreement.
Mrs. May opted to have her government act unilaterally to delay the parliamentary vote, rather than putting the matter to a vote of the House of Commons. John Bercow, who as speaker of the house oversees debates, warned on Monday that such a move, after several days of debate, “will be thought by many members of this house to be deeply discourteous,” and that “many colleagues from across the house have registered that view to me in the most forceful terms.”
In the 2016 referendum on whether Britain should remain in the European Union, Mrs. May did not support the leave option, which won 52 percent of the vote, but she has promised consistently to carry out that mandate. Under current law, Britain will withdraw on March 29.
Many British lawmakers who oppose Brexit still hope to prevent it from happening, aiming to hold a second referendum and get a different result.
For members of Parliament who support Brexit, the biggest sticking point in Mrs. May’s deal is the arrangements for Northern Ireland.
For many years, there has been no “hard” border between Ireland, a European Union member nation, and Northern Ireland, a part of Britain — no walls, no checkpoints, and no barrier to the movement of people and goods. Ireland, Britain and the European Union all support keeping it that way, but it is unclear how to do so if Britain is to have its own trade, customs and immigration rules.
Under the agreement, Britain would remain largely within the European Union’s customs and trade system for the next two years while a long-term pact is negotiated.
But if such a pact were not reached by December 2020, the deal provides a “backstop” that would keep the border open by maintaining a close customs relationship between Britain and the European Union, and keeping Northern Ireland aligned to the union’s rules.
Hard-core Brexit supporters argue that Mrs. May’s deal ties Britain indefinitely to the bloc’s rules, and could also create one system for Northern Ireland and another for the rest of the country.