Who is Boris Johnson, Britain's new prime minister?

Boris Johnson, the former London mayor who campaigned on a pro-Brexit message, is Britain's next prime minister, as announced Tuesday.

Johnson's beat out rival Jeremy Hunt, the current secretary of state for Foreign and Commonwealth Affairs. He will replace Theresa May, who announced her resignation in late May, amidst failed Brexit negotiations.

Since the announcement of her resignation, U.S. President Trump has backed Johnson. He wasted no time in congratulating the new prime minister.

After members of the governing Conservative Party voted Monday, Johnson was favored to win. In the British Parliament system, the leaders of the political party with the most members of Parliament vote, rather than the public. In this case, the Conservative, or Tory party will vote, which is 0.25 percent of the 66 million British people, according to The Associated Press.

Ahead of Johnson's likely takeover, Senior Foreign Minister Sir Alan Duncan announced his resignation in a letter to May, while several other Tory leaders have threatened to do the same.

“It is tragic that just when we could have been the dominant intellectual and political force throughout Europe, and beyond, we have to spend every working day working beneath the dark cloud of Brexit,” Duncan wrote in the letter.

Two senior cabinet ministers, Chancellor Philip Hammond and Lord Chancellor David Gauke, also pledged to leave over the no-deal issue if Johnson wins.

WHO IS BORIS JOHNSON? Five Fast Facts:

1. Johnson, a former journalist turned politician, grew popular through his satirical criticism of the 28-nation European Union.

2. He was a member of Parliament for Henley from 2001 to 2008, and is currently the MP for Uxbridge and South Ruislip.

3. The Conservative politician is best known for being the mayor of London between 2008 and 2016, and during this time oversaw the 2012 London Olympics and introduced the public bicycle system called "Boris Bikes."

4. Johnson has been critical of Trump, most recently speaking out about his "unacceptable" tweets regarding four Democratic congresswomen, but Trump continues to support the Brexit hardliner.

5. Johnson has promised tax cuts for higher earners and plans to emphasize green jobs. In an Interview with The Sunday Times, Johnson refused to pay the £39 billion (about $49.6 billion) 'Brexit divorce bill' unless terms of UK’s exit from the EU improve.

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Britain’s next scheduled election is in 2022 and the incoming prime minister may call an early vote if he can’t get his Brexit plans approved, and seek a new mandate from the electorate.