British Prime Minister Boris Johnson on Tuesday sought to outlaw extending the Brexit transition period beyond the end of 2020, as he prepared to put the EU divorce deal before MPs.

Johnson won a big majority in last week’s general election on a promise to “get Brexit done” by taking Britain out of the European Union by the end of January.

A transition period will then follow, during which London and Brussels hope to negotiate a trade agreement before the end of December next year.

European leaders have said the 2020 deadline would be too tight to complete a comprehensive deal, reviving fears of a “no-deal” outcome that could cause fresh uncertainty and chaos.

Johnson held his first cabinet meeting since the election on Tuesday, welcoming back his ministers after what he called a “seismic” result.

“The voters of this country have changed this government and our party for the better and we must repay their trust now by working flat out to change our country for the better,” he said during the meeting at his Downing Street office.