Prime Minister Boris Johnson announced on Thursday that he would resign, ending an unprecedented political crisis over his future that has roiled the United Kingdom in recent weeks.

"It is clearly now the will of the parliamentary conservative party that there should be a new leader of that party and therefore a new prime minister," Johnson said outside his office at 10 Downing St. in London.

Johnson said the process to select his successor would begin immediately and a timetable for the change in leadership would be announced next week.  

He said it was "painful" for him to leave office but conceded he had failed to push back against an onslaught of opposition from his own party ministers urging him to resign.

"I am sad to be giving up the best job in the world, but thems the breaks," Johnson said in brief remarks Thursday.

Johnson said he has tried to convince his colleagues over the past few days that it would be “eccentric” to change governments when his government is delivering and his party is just a few points behind in the polls.