Boris Johnson has said he will run to be leader of the Conservative Party in Britain.
The country's former foreign secretary told a conference in Manchester that he would enter the race to succeed Theresa May if a vacancy arises.
He declined to answer questions from journalists as he left the event.
British Prime Minister Theresa May has promised to step down if the UK parliament ratifies the country's Brexit deal.
Mrs May is immune to ousting by MPs until December 2019 - after winning a vote of confidence last year.
Some backbenchers are trying to change the rules so another vote can be held more quickly, while others - including her former co-chief of staff - are calling for her to go.
Mr Johnson was picked as one of the leaders of the 'Vote Leave' campaign for Mrs May's cabinet when she took over in the aftermath of the 2016 referendum.
He was Britain's foreign secretary for two years, before quitting over Mrs May's plan for the future UK-EU relationship after Brexit.
He was also followed out of the British cabinet by then-Brexit secretary David Davis.
According to one MP, Mr Johnson's leadership campaign has been three years in the making.
He did not enter the race for prime minister back in 2016, declaring hours before the deadline for nominations closed that the new leader "cannot be me", citing "the circumstances in parliament".
The UK is now on course to leave the European Union by October 31st, or earlier if the parliament ratifies a deal.
Meanwhile Mrs May will set out the timetable for her departure following one final attempt to get the Brexit deal passed by MPs.
She held talks with senior Conservatives in Westminster on Thursday, where she was pressed more clarity on her timetable for exiting Downing Street.
Graham Brady, chairman of the 1922 Committee of backbench Consercative MPs, said he will meet with Mrs May to agree the details of her exit from Downing Street early next month.
This will come after a vote on the Withdrawal Agreement bill, which enshrines the Brexit plan into UK law, in the week beginning June 3rd.
Earlier this year, Mrs May promised to go once her Brexit deal has been passed by MPs.