BIRMINGHAM, England — Outlining a timetable for Britain to leave the European Union in the spring of 2019, Prime Minister Theresa May on Sunday put immigration at the center of her strategy for withdrawal, suggesting that Britain could be headed for a “hard Brexit,” or clean break, from the bloc.
In a speech at the start of the Conservative Party’s annual convention here, May said Britain would formally initiate exit negotiations by the end of March. Those talks will be governed by a two-year deadline unless all members of the bloc agree to prolong them.
Previously, May had said only that the talks, under Article 50 of an EU treaty, would not begin before the end of this year — a delay designed to buy time for the government to work out its negotiating stance.
On Sunday, May also began to lay down her priorities for a deal on withdrawal, known as Brexit, including the power to control immigration and reject EU rules that allow people to move and settle across national frontiers.
“We have voted to leave the European Union and become a fully independent, sovereign country,” May said to applause from delegates. “We will do what independent, sovereign countries do. We will decide for ourselves how we control immigration. And we will be free to pass our own laws.”
That position strikes at the heart of the usual trade-off by countries that have unfettered access to Europe’s internal market of about 500 million people, but that also accept the freedom of Europeans to cross frontiers and live and work in any member state.
While May said she wanted the “maximum” scope for British companies to trade inside the EU’s single market, she added that Britain would not accept the right of EU law to trump national legislation — a pillar of the single market.
May also spoke of striking free-trade deals with new partners, suggesting that Britain would leave Europe’s Customs Union, which lays down common tariffs but prevents member states from striking independent arrangements with other countries.
Her speech left many details unclear and undoubtedly represents a tough opening bid before next year’s talks, which will probably be complex and fraught with disagreement.
She argued that the country’s new relationship with the European Union would be unique and rejected the idea that there was a clear division between a “hard” Brexit and a “soft” one with closer economic ties, although there are signs of deep differences within her Cabinet on the issue.
Ideally, May would like to regain the ability to curb migration from the Continent while keeping full access to the EU’s single market.
In an interview in The Sun published Saturday, Boris Johnson, the foreign secretary, argued that Britain’s policy was “having our cake and eating it.”
Yet across the English Channel, there has been no sign of compromise, and EU politicians have made it clear a trade-off is required from Britain.
Overall, May’s speech suggested that she would emphasize the right to curb immigration even if that meant securing less favorable access to European markets.
David Davis, the minister responsible for negotiating Brexit, underscored the position that trading arrangements were not the only — or even the most important — part of the British equation.
“We want to maintain the freest possible trade between us, without betraying the instruction we have received from the British people to take back control of our own affairs,” Davis told the convention.
May insisted in her speech — the first of two to the convention — that Scotland would leave the European Union, too, and had “no opt-out from Brexit.” In the referendum that determined Britain’s exit from the union, the majority of Scots voted to remain.
She also announced plans to start the domestic legislative process for Brexit next year by asking Parliament to repeal the 1972 European Communities Act, which allowed Britain to join the EU’s predecessor.
Although this new legal step would not come into effect until Britain left the bloc, it would transfer European legislation — including laws to protect labor rights — into British law. Parliament would then be able to decide at a later point which laws to keep.
In a statement, Carolyn Fairbairn, the director general of the nation’s main business lobby group, the Confederation of British Industry, welcomed that development but highlighted the anxieties of many companies.
“With a rapid timetable pointing to an exit from the EU in spring 2019, businesses need to know the government’s ambition on the fundamental issues of skills and barrier-free access to EU markets as soon as possible,” she said.
“Businesses cannot continue to operate in the dark,” she added, because “the decisions they face today are real and pressing.”
There have been warnings in recent week from manufacturers, including carmakers that fear they may face tariffs, and from financial services companies that worry about their ability to do business across Europe from London.
Still, the outcome of the June referendum was interpreted by many politicians, including May, as a rejection of the EU’s policy of free movement of people, which has allowed hundreds of thousands from Southern and Eastern Europe to settle in Britain.
The European Union aims to guarantee the free movement of goods, capital, services, and people across its frontiers, and for many of Europe’s policymakers it would be a betrayal to allow Britain to enjoy the economic benefits while rejecting free movement of people.
In a recent interview with the BBC, Prime Minister Matteo Renzi of Italy said it would be “impossible” to give British people more rights than others outside the European Union.
The president of the European Central Bank, Mario Draghi, has said that Britain should not be granted any special favors on single-market access and that “any outcome should ensure that all participants are subject to the same rules.”