UK Prime Minister Boris Johnson said on Tuesday that it will legislate to ensure a post-Brexit transition period does not extend beyond 2020, sending the pound sinking as the European Union warned of a race against time to agree new trade terms.

A transition period will follow until December 31, 2020, during which London and Brussels hope to negotiate a new economic and security partnership to replace 46 years of integration.

On Tuesday, UK has an option to extend the transition but Johnson refuses to, and intends to enshrine the 2020 date in legislation, his office said.

At his first cabinet meeting since the election on Tuesday, Johnson pledged to work “24-hours-a-day, flat out” to deliver on his election promises.

The EU’s chief Brexit negotiator Michel Barnier said the bloc would “do the maximum” to try to agree a new partnership by the 2020 deadline, and avoid a highly disruptive “no deal” divorce.

PM Johnson’s government intends to present a bill to parliament this week on Friday to enable Britain to leave the European Union next month.

After Johnson claimed huge victory, European leaders will charge EU negotiator Michel Barnier with negotiating a close trade deal with Britain.

A landslide Conservative win would mark the ultimate failure of opponents of Brexit who plotted to thwart a 2016 referendum vote through legislative combat in parliament and prompted some of the biggest protests in recent British history.

Johnson was re-elected Prime Minister following his landslide victory in the December 12 general election, deemed as one the UK’s most decisive and crucial.

Labour leader Jeremy Corbyn said that he would stand down as his party faced its worst electoral defeat in 84 years, but he did not set a date for his departure, adding that he would remain in charge during a period of reflection.