(Bloomberg) -- Prime Minister Rishi Sunak is under growing pressure from members of his Cabinet to take the UK out of the European Convention on Human Rights, a move that could open a dramatic rift in the government ahead of a general election expected next year.

On the first day of the governing Conservative Party’s annual conference in Manchester, Levelling Up Secretary Michael Gove joined Business Secretary Kemi Badenooch in saying the UK’s membership of the ECHR, which some Tories blame for preventing the government from deporting asylum seekers to Rwanda, should be up for discussion. Home Secretary Suella Braverman is a long-time advocate of leaving the convention.

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Sunak has made stopping small boats carrying asylum-seekers arriving from France a key priority he wants voters to measure him by. Deporting arrivals to Rwanda is a central part of that policy, but the Strasbourg court that oversees the ECHR has intervened to block the effort. Meanwhile, the British Supreme Court is also expected to rule by the end of the year on whether the plan is legal.

Sunak’s team expects to win the British case, but, should they fail, pressure on the premier to withdraw will grow. The UK should “keep every option open,” Gove said Sunday, when asked about the convention. Gove supported Badenoch to be party leader last year.

The issue is potentially seismic, given the UK was heavily involved in drafting and signed in 1951. Though not administered by the European Union, it has become a focal issue of Brexit supporters, who see it as enabling foreign control of Britain’s immigration policy. Pulling out would force Sunak to again counter charges that the UK is surrendering its leadership on the world stage. 

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In the ECHR’s seven-decade history, only two nations have abandoned it: Greece did during a period of military rule, but later rejoined. President Vladimir Putin’s Russia also quit the framework. The treaty’s basic principles cover things like free elections, respect for property rights and access to education.

“I don’t feel that in order to achieve what we need to achieve, to protect our borders, we are necessitated to leave the ECHR,” Foreign Secretary James Cleverly said. 

Sunak would also face an immediate headache if he took the UK out. The convention is written into the peace treaty which ended decades of sectarian violence in Northern Ireland in 1998. “What is the alternative for the Good Friday Agreement?” Security Minister Tom Tugendhat said.

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