FILE - U.S. President Donald Trump shakes hands with Boris Johnson, left, then the British foreign secretary, as they take part in a session on reforming the United Nations at U.N. Headquarters in New York, Sept. 18, 2017.
FILE - U.S. President Donald Trump shakes hands with Boris Johnson, left, then the British foreign secretary, as they take part in a session on reforming the United Nations at U.N. Headquarters in New York, Sept. 18, 2017.

If U.S. President Donald Trump is unlike anyone who’s occupied the Oval Office, the same could be said of new British Prime Minister Boris Johnson when it comes to 10 Downing Street. Both are unpredictable and unconventional.

Their readiness to break with custom and their checkered personal lives — let alone their distinctive hairstyles — have attracted comparisons. Both have surfed populist political waves to power.

The U.S. president sees an affinity, lauding Johnson as “Britain Trump.” And there are high expectations among Trump supporters and British Brexiters that the Anglo-American relationship is about to be spruced up in new ways. Their aides talk enthusiastically of a revived relationship that has been buffeted in the past two years.

WATCH: Henry Ridgwell report

The lack of personal chemistry between Trump and Johnson’s predecessor, Theresa May, did not help Washington and London navigate serious policy differences over Iran, climate change and multilateral cooperation. Those policy differences remain.

Nonetheless the Brexit-boosting Trump has dubbed Johnson a “good guy, a good friend of mine.”

The U.S. president recently told reporters, “He will be a good prime minister. He has what it takes, they needed him for a long time.”

Speaking last week at a rally in Washington, Trump said: “We have a really good man. He’s going to be the prime minister of the U.K. now, Boris Johnson… He’s tough and he’s smart.”

For domestic political reasons, Johnson publicly has not been as fulsome in praise of the U.S. leader. Britons have an overwhelmingly unfavorable view of President Trump, with recent polls showing just 21 percent of them having a positive opinion of the president. In the past Johnson has even been openly critical of him.

As mayor of London, a liberal bastion, he was dismissive of Trump. “The only reason I wouldn't visit some parts of New York is the real risk of meeting Donald Trump,” he once said.

But with his shift to the hard core Brexit wing of the Conservative party from the liberal One Nation faction, Johnson changed his opinion of Trump.

By last year he emerged a fan, enthusiastically telling British lawmakers at a private dinner, “I am increasingly admiring of Donald Trump.”

“Imagine Trump doing Brexit. What a fantastic idea," Johnson added.  "How would, Donald Trump have approached our Brexit negotiations? There’d be all sorts of breakdowns, there’d be all sorts of chaos. Everyone would think he’d gone mad. But actually you might get somewhere.”

With his bellicose “do or die” pledge to leave the European Union on October 31, some argue the new British prime minister is emulating Trump. Michel Barnier, the EU’s top Brexit negotiator, has described Johnson as “combative.”

FILE - 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.

Campaigning to replace May, Johnson offered the highest form of flattery by imitating Trump, echoing some of the U.S. leader’s slogans, promising among other things to “make Britain great again.”

Both men share a disdain for the European Union — although Johnson is a latecomer to Euro-skepticism, a position many believe he adopted because it offered him a clearer path to the top job.

So will it all be smooth sailing when it comes to the transatlantic partnership between the two? Will Trump-Johnson emerge as a 21st-century pairing comparable to the 20th century’s Reagan-Thatcher or Clinton-Blair?

Nile Gardiner, a former Thatcher adviser and now an analyst at the Washington’s Heritage Foundation, a conservative research group, believes Johnson can refresh transatlantic ties.

FILE - Britain's Prime Minister Boris Johnson speaks at the House of Commons in London, July 26, 2019.

“The New York-born Johnson,” he predicted in Britain’s Daily Telegraph, “will be the most popular British prime minister in the U.S. since Margaret Thatcher, with a public profile that greatly exceeds that of his immediate predecessors.” Johnson’s optimism and can-do energy is something Americans appreciate, Gardiner argues.

He and fellow British Brexiters and American Neoconservatives are urging Johnson not to hold back from getting firmly in bed with Trump, fearing if he does not, he could blow his chances of pulling off a post-Brexit trade deal with the United States that Britain dearly needs.

A Trump adviser told VOA that there’s a salutary lesson for Johnson in the trajectory of Trump’s relationship with France’s Emmanuel Macron, which started out after a state visit to Paris as a bromance but soured quickly.

But there’s also danger for Johnson cleaving too closely to Trump. Johnson’s own father, Stanley, a former EU lawmaker, has sounded a note of caution, saying his son needs to “be careful not to be too slavishly geared to America.” Talking to an American broadcaster, he said, “oddly enough, I think almost the most important thing we can do is [after] we leave Europe is to build bridges with Europe.”

Maintaining a balancing act between Washington and Brussels will be hard. Friends say Johnson does not “do subtle” so well — neither for that matter does Trump, who sees foreign policy as a zero-sum game, and likes to win. Trump was frustrated with May’s EU withdrawal agreement — that failed to gain British parliamentary approval — arguing it would block and restrict a trade deal between the U.S. and Britain.

FILE - Members of the Brexit Party turn their back to the assembly as the European anthem is played, during the first plenary session of the newly elected European Parliament in Strasbourg, France, July 2, 2019..

But Johnson is not as enthusiastic as Nigel Farage, the head of Britain’s Brexit party and a special favorite of the U.S. president. He favors exiting the EU without a deal. But aides and friends say, despite all the tough talk, Johnson would still prefer to be leaving the trading bloc with an exit agreement — and that would likely restrict trade deals with non-EU countries. Farage is seen by Johnson’s aides as a potential danger — someone who could poison the president’s views of Johnson, if Britain’s new prime minister fails to take his country out of the EU by October 31.

A Britain that exits without a deal will also need more than just a trade pact with the U.S., and is looking towards Asia, specifically Beijing, for a commercial boost. Chinese investment and trade has never been more important for Britain.

In an interview with Hong Kong’s Phoenix Television last year Johnson, when he was Britain’s foreign secretary, didn’t hesitate to lavish praise on China, saying, “we are very pro-China.” He said his daughter was learning Mandarin in China. He pointed out Britain “was the first country to sign up to the Asian Infrastructure Investment Bank” and said he was “very enthusiastic” about Chinese President Xi Jinping's signature Belt and Road Initiative (BRI), the ambitious trillion-dollar transcontinental trade and infrastructure project.

BRI, nicknamed the New Silk Road, has prompted disquiet in Washington, as well as Brussels. Both U.S. Secretary of State Mike Pompeo and National Security Adviser John Bolton have targeted BRI, voicing concern about Beijing's growing political clout in Europe, the Middle East and Africa and its use of commerce as a tool of political statecraft.

Johnson cannot risk losing a huge market like China, and like his predecessor in Downing Street he may well discover the snag of balancing the geo-political requests of Britain’s traditional ally with the ambitions of Beijing, warn analysts and diplomats. Beijing hopes a trade deal will not only make Britain a secure base for Chinese companies looking to enhance their global brand value and make new acquisitions, but will expect a quid pro quo and for the British to become advocates within the West for China's interests, say China-watchers.

May ran full tilt into the conundrum earlier this year and triggered a transatlantic spat when she disregarded U.S. security alarms and offered provisional assent to the Chinese tech giant Huawei to help build Britain’s next-generation 5G mobile phone network.

Washington fears Huawei will act as a Trojan horse for China's espionage agencies, allowing Beijing to sweep up data and gather intelligence, compromising not only Britain's security, but also America's, say U.S. officials. On Iran, too, Johnson faces a hurdle. How will Trump react if Britain does not now back his effort to apply maximum pressure on Tehran?