(Bloomberg) -- President Donald Trump on Tuesday congratulated Boris Johnson, the public face of the Brexit campaign, who won the Conservative Party contest to succeed Theresa May as British prime minister.

“He will be great!” Trump said on Twitter.

After a six-week leadership race, which he led from the start, Johnson defeated his rival Foreign Secretary Jeremy Hunt in a ballot of the Tory party’s 180,000 members. He takes over a country in crisis and a government marked by fissures.

The result marks the end of a bruising battle for the biggest job in British politics and the start of what threatens to be a brutal new phase in the civil war inside the government over Brexit.

The incoming prime minister has just 100 days to negotiate a new divorce deal with the European Union before the U.K. is due to leave the bloc at the end of October.

Trump considers Johnson a like-minded friend, while EU leaders view him with deep suspicion. And with an escalating crisis with Iran — the U.S. and Europe are divided over preserving the 2015 nuclear agreement and Tehran last week seized a U.K.-flagged oil tanker — his allegiances will be tested early.

To contact the reporter on this story: Terrence Dopp in Washington at tdopp@bloomberg.net

To contact the editors responsible for this story: Kasia Klimasinska at kklimasinska@bloomberg.net, Elizabeth Wasserman, Kathleen Miller

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