London  - Michael O'Leary, the outspoken pro-EU chief executive of budget airline Ryanair, recently joined a growing number of critics who feel Prime Minister Theresa May's Brexit negotiations are "going nowhere."

"They are a bit of a shambles, and they need a bit of leadership," O'Leary told Sky News.

Ahead of May's much-anticipated Brexit speech in Florence on Friday, speculation is mounting over whether the under-pressure prime minister or a rival inside her Conservative party could try to provide that leadership.

In what many analysts see as the latest sign of division, Foreign Secretary Boris Johnson - a leadership contender before May won the race to replace David Cameron in July 2016 - set out his personal "vision for a bold, thriving Britain enabled by Brexit" in The Times on Saturday.

Johnson revived the controversial claim, first used by the Leave campaign he led into last year's Brexit referendum, that leaving the European Union could save Britain more than 350 million pounds (455 million dollars) per week to be spent on public services.

Home Secretary Amber Rudd accused Johnson of attempting to position himself as a "back-seat driver" of Brexit, while David Norgrove, head of the government's statistics office, wrote an open letter complaining that Johnson's weekly total of 350 million pounds "confuses gross and net contributions" to the EU and was "a clear misuse of official statistics."

Johnson rejected Norgrove's criticism and said he was "looking forward" to May's speech in Florence.

"All behind Theresa for a glorious Brexit," he wrote on Twitter.

"We are all going to the same destination"

But Colin Talbot, a professor of government at Manchester and Cambridge universities, said it appears that Johnson "wants to position himself as Leader of the Hard Brexit Brigade for the leadership battle to come."

The Conservatives are in "almost open civil war," while their main rivals, Labour, are in "suppressed civil war," Liberal Democrat leader Vince Cable said on Monday.

"Boris is Boris," May told reporters travelling with her to Canada on Monday. "This government is driven from the front and we are all going to the same destination," she said.

"We are all agreed as a government about the importance of ensuring the right deal for Britain, the right withdrawal agreement but also the right deal on a special partnership between the EU and UK for the future."

Despite her recent insistence that she is "not a quitter" and will lead the Conservatives into another general election in 2022, Simon Usherwood, a Brexit-focussed political analyst at the University of Surrey, said she remains "a dead woman walking."

That has been the view of many observers since May called a disastrous snap election in June.

She surprisingly lost her parliamentary majority in the election, amid a surge in support for left-wing Labour leader Jeremy Corbyn, forcing her to rely on backing from 10 lawmakers from Northern Ireland's Democratic Unionist Party in key votes.

"She's fatally compromised herself with the party, and the party is not a sympathetic organization," Usherwood told dpa.

It would take a "pretty astounding turnaround" for May to remain the long-term leader, he said.

"I think at this point it's convenient to keep her in [office], because if things are looking bad she may as well take the blame, and then the new person comes in and cleans up and gets a bounce off that," Usherwood said.

Different views in party unity

Chancellor Philip Hammond, who has promoted a "pro-business" Brexit with strong transitional arrangements to protect the economy after Britain leaves the EU in March 2019, and Liam Fox, a pro-Brexit trade minister who argues that Britain could survive leaving the EU with no deal, wrote a joint article last month that was seen as a show of unity by the Conservatives.

Britain will definitely leave the EU customs union and single market but could agree a "time-limited" transition to "give business greater certainty," Hammond and Fox wrote in The Telegraph.

But Usherwood said their intervention failed to hide the cracks in party unity.

"You're still getting the different views coming through from individuals," he said.

"They might have patched things over for that [article] but there's still lots that they don't agree on."

Usherwood said he saw "no consensus view in cabinet or in senior levels of the Tory party."

"So it's the same problem that there's been all the way since last June: There's no plan; and even if there were a plan, there's nobody who's got a clear ability to make it happen."