London (CNN) Boris Johnson, former London mayor and ardent critic of Theresa May's Brexit strategy, has thrown his hat into the ring to replace the British Prime Minister, announcing he will run for leadership of the Conservative Party when she steps down.

"Of course I'm going to go for it," he told a BBC news anchor at a business conference in Manchester, when asked if he would be a candidate in a future Conservative leadership election.

The winner of that contest will automatically become Prime Minister, taking center stage in the chaotic Brexit process that has plunged Britain into one of its worst postwar political crises.

A senior figure in the Conservative Party, Graham Brady, said May had agreed she would set a "timetable for the election of a new leader" after her Brexit deal is put to lawmakers for a fourth and final time in early June. The deeply unpopular deal has already been soundly rejected three times by Parliament.

Johnson, a former Mayor of London, has long held leadership ambitions. He has been an arch critic of May's Brexit approach -- although he ultimately voted in favor of her plan on the third occasion it was placed before MPs.

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