As he announced his resignation, British Prime Minister Boris Johnson said the nature of politics is that "no one is remotely indispensable."

"As we've seen at Westminster, the herd instinct is powerful — when the herd moves, it moves. And my friends, in politics, no one is remotely indispensable," he said Thursday. "And our brilliant and Darwinian system will produce another leader, equally committed to taking this country forward through tough times."

Johnson said he will support his successor as much as he can. "To that new leader — whoever he or she may be — I say I will give you as much support as I can."

He also addressed the British public, saying he is sad to be leaving the "best job in the world."

"To you, the British public: I know that there will be many people who are relieved and perhaps, quite a few will also be disappointed. And I want you to know how sad I am to be giving up the best job in the world."