MANCHESTER, England (Reuters) - British Foreign Secretary Boris Johnson offered Theresa May unsolicited public advice about how to make Brexit a success on Tuesday, delicately testing the extent of the prime minister’s weakened authority while pledging overt loyalty.

Britain's Foreign Secretary Boris Johnson addresses the Conservative Party conference in Manchester, October 3, 2017. REUTERS/Phil Noble

Alongside public proclamations of backing for May, he used media articles and interviews ahead of the Conservative Party Conference in Manchester to offer up his own vision of a bold Brexit.

After praising May for winning a snap June election which lost her party its majority in parliament, Johnson used his main speech to say that her top ministers were united behind “every syllable” of her Brexit plans set out last month in Florence.

“The whole country owes her a debt for her steadfastness in taking Britain forward, as she will, to a great Brexit deal, based on that Florence speech on whose every syllable, I can tell you, the whole cabinet is united,” Johnson said.

Just hours later, though, the man who led the main ‘leave’ campaign in the 2016 referendum on Britain’s EU membership told activists at a separate event that there was far too much gloom surrounding Brexit.

He then sketched out his own views on how Britain’s exit would look and how Britain might need different regulations on everything from data to bioscience.

“I campaigned on a slogan of... ‘Take Back Control’.... I think that’s what the prime minister also believes in very strongly,” Johnson told the gathering.

“If you’re going to do this, do it well. Do it in such a way as to get a great result for the UK,” he said. “We want an arrangement that means we are not just locked in strict rotational orbit around the EU.”

“SACK BORIS”

Johnson, widely regarded in Britain as concealing a fierce political ambition behind a clownish exterior, has overshadowed the party conference which May had hoped to use to claw back some authority after her election gamble went so wrong.

Arriving with his trademark blonde hair tousled and rummaging through a suit jacket pocket, Boris enthused Conservative members but was careful to make no explicit pitch to replace May.

Ahead of Johnson’s speech, May had repeatedly faced questions from reporters about whether she would sack Johnson after he appeared to undermine her Brexit strategy by setting out his own vision. She has sidestepped those questions.

The European Parliament savaged the British government’s handling of Brexit negotiations on Tuesday, voting against opening talks yet on future trade and condemning disarray in May’s team.

A German ally of conservative Chancellor Angela Merkel, Manfred Weber, said British cabinet in-fighting was putting a deal at risk and called on May to sack Johnson.

PM BORIS?

But Johnson also provided a rare spark in Manchester where Conservative ministers lined up to cast the opposition Labour Party as dangerous Marxists while failing to offer any striking new policies.

“To me, that was real leadership: motivating, inspirational. What’s a good leader? It’s somebody who can do that,” said Vanessa Churchman a local government official from the Isle of Wight in the south of England. “Everybody who goes away from here will feel inspired.”

At previous party conferences, Boris, as he is widely known in Britain, also repeatedly upstaged then-prime minister David Cameron, though after the referendum sank Cameron’s career, Johnson dropped out of the race to be leader when a colleague broke a pact to back him.

While Johnson is popular with party members, many Conservative lawmakers are angry that he has overshadowed May with what they say were unhelpful and disloyal interventions.

May, the staid daughter of a vicar, has a presentational style that is in many ways the polar opposite of Johnson’s swashbuckling on-stage persona. She is due to close the conference on Wednesday.