Boris Johnson, a leadership candidate for Britain's Conservative Party, poses for a picture as he visits the Thames Valley Police Training Centre in Reading, Britain, July 3, 2019.

Boris Johnson, a leadership candidate for Britain's Conservative Party, reacts as he visits the Thames Valley Police Training Centre in Reading, Britain, July 3, 2019.

British PM Boris Johnson and Jeremy Hunt appear on BBC TV's debate with candidates vying to replace British PM Theresa May, in London, Britain June 18, 2019. Jeff Overs/BBC/Handout via REUTERS

Boris Johnson, a leadership candidate for Britain's Conservative Party, visits the Thames Valley Police Training Centre in Reading, Britain, July 3, 2019.

Boris Johnson, a leadership candidate for Britain's Conservative Party, attends a hustings event in Manchester, Britain, June 29, 2019. Image used for illustrative purpose.

Conservative Party leadership candidate Boris Johnson gestures as he talks during the launch of his campaign in London, Britain June 12, 2019.

Jeremy Hunt, a leadership candidate for Britain's Conservative Party, attends a hustings event in Manchester, Britain, June 29, 2019.

Jeremy Hunt, a leadership candidate for Britain's Conservative Party, leaves BBC studios in London, Britain June 30, 2019.

Conservative leadership candidate Boris Johnson looks out from the bridge of the Isle of Wight ferry St Faith, as it sets sail from Portsmouth, Britain June 27, 2019. Andrew Matthews/Pool via REUTERS

Boris Johnson, a leadership candidate for Britain's Conservative Party, poses as he visits the Thames Valley Police Training Centre in Reading, Britain, July 3, 2019. REUTERS/Dylan Martinez/Pool - RC111D049F40

Jeremy Hunt, a leadership candidate for Britain's Conservative Party, speaks during a hustings event in Belfast, Northern Ireland, July 2, 2019. Peter Morrison/Pool via REUTERS

Boris Johnson, a leadership candidate for Britain's Conservative Party, speaks to media as he visits the Thames Valley Police Training Centre in Reading, Britain, July 3, 2019.

Boris Johnson, a leadership candidate for Britain's Conservative Party, holds a method of entry equipment as he visits the Thames Valley Police Training Centre in Reading, Britain, July 3, 2019.

Britain's Conservative Party leadership candidate Jeremy Hunt arrives to speak at a hustings event in Exeter, Britain, June 28, 2019.

Conservative Party leadership candidate Jeremy Hunt returns from his morning run in London, Britain July 1, 2019.

Jeremy Hunt, a leadership candidate for Britain's Conservative Party, delivers a speech on his Brexit plan, in London, Britain, July 1, 2019. Frank Augstein/Pool via REUTERS

Conservative party leadership contender Boris Johnson sits in a boat under construction at the Venture Quay boatyard during a visit to the Isle of Wight, Britain June 27, 2019. Dominic Lipinski/Pool via REUTERS

Jeremy Hunt, a leadership candidate for Britain's Conservative Party, leaves his residence in London, Britain July 1, 2019.

Boris Johnson, a leadership candidate for Britain's Conservative Party, poses as he visits the Thames Valley Police Training Centre in Reading, Britain, July 3, 2019.

Britain's Foreign Secretary Jeremy Hunt speaks during the launch of his campaign for the Conservative Party leadership, in London, Britain June 10, 2019.