The House of Commons voted by a wide margin against a call to join the European Economic Area — a club that includes the EU nations and Norway — after Conservative and opposition Labour leaderships opposed it.
Lawmakers also rejected, much more narrowly, calls to keep the U.K. in a customs union with the EU. The votes came after two days of bruising debate on the government's key piece of Brexit legislation — the European Union Withdrawal Bill, intended to disentangle Britain from the 28-nation bloc after four decades of membership. In a series of votes the House of Commons largely reversed changes inserted by Parliament's upper House of Lords that would have softened the terms of Brexit.
But it is likely only a temporary reprieve. Many lawmakers said it seemed likely that Britain would have to remain in a customs union with the EU, even though the government insists it will leave. The government says leaving the customs union will free the country to strike trade deals around the world. But many businesses fear it will mean tariffs or other barriers for British goods in Europe.
It also threatens the currently invisible border between the U.K.'s Northern Ireland and the Republic of Ireland, an EU member. The withdrawal bill promises that the border will stay open and there will be no "physical infrastructure, including border posts, or checks and controls." But the British government has not said how that can be achieved if the U.K. and the EU have different customs rules.
Pro-EU Conservative Heidi Allen said it was inevitable "we will have to come to a customs union agreement," even if it was given another label. "Partnership, love dance — don't care what you call it, that's what we will need to avoid any border to Northern Ireland," she said.
The government was forced to give ground to pro-EU lawmakers in one key area, promising that Parliament would get more say over the U.K.-EU divorce deal. Many pro-EU lawmakers want Parliament to be able to send the government back to the negotiating table if they don't like the terms of the deal, or if talks with the bloc break down.
Pro-Brexit lawmakers worry Parliament could use that power to delay Britain's departure, or stop it altogether. May said the government would amend the bill to address legislators' concerns, but warned that "I cannot countenance Parliament being able to overturn the will of the British people."
"The British people voted to leave the European Union, and as prime minister I'm determined to deliver that," she told lawmakers. It has been two years since Britain voted by 52-48 percent to exit the EU, and there are eight months until the U.K. is due to leave the bloc on March 29, 2019.
But Britain — and its government — remain divided over Brexit, and EU leaders are frustrated with what they see as a lack of firm proposals from the U.K about future relations. May's government is divided between Brexit-backing ministers such as Foreign Secretary Boris Johnson who support a clean break with the EU, and those such as Treasury chief Philip Hammond who want to keep closely aligned to the bloc, Britain's biggest trading partner.
A paper laying out the U.K. government position on future relations, due to be published this month, has been delayed until July because the Cabinet cannot agree on a united stance. Brexit has also complicated relations between the British government and Scotland, where a majority voted in 2016 to stay in the EU. Scottish National Party lawmakers walked out of the House of Commons Wednesday to protest the short amount of time given to debate Scotland-related issues the day before — 20 minutes out of a six-hour session.
The pro-independence party accuses the British government of trying to seize powers that will be handed back from Brussels after Brexit and which the SNP believes should go to Scotland's Edinburgh-based parliament.
Ian Blackford, the SNP leader in Parliament, called the situation "a democratic outrage." "Scotland's voice has not been heard," said Blackford, who was expelled from the chamber for repeatedly challenging the Speaker on the issue, sparking a walkout by his colleagues.