BORIS Johnson has returned to the UK to plot a bid to return as prime minister in a move that has divided opinion even among former allies – after Rishi Sunak became the first candidate in the race to meet the nomination requirement of 100 MPs.

Johnson arrived at Gatwick Airport yesterday morning with his family after breaking off a holiday in the Dominican Republic following Liz Truss’s forced resignation on Thursday.

Sky News photographed the former prime minister and his wife Carrie Johnson in economy on an overnight British Airways flight back from the Caribbean with their children and said the MP received “one or two boos” as he boarded.

READ MORE: Boris Johnson reaches 100 Tory MP threshold in leadership race to become UK prime minister

Johnson’s ally Sir James Duddridge claimed he has the backing of the 100 MPs required to be on tomorrow’s ballot but many of them have not publicly declared that support.

He is likely to be opposed in the leadership race by his former chancellor Sunak, whose resignation was key in Johnson’s departure from Downing Street this summer, as well as Commons Leader Penny Mordaunt.

Johnson and Sunak are yet to formally declare that they will run.

He has won the support of six Cabinet ministers: Ben Wallace, Jacob Rees-Mogg, Simon Clarke, Chris Heaton-Harris, Alok Sharma and Anne-Marie Trevelyan.

Sunak has 109 public backers, while Mordaunt – who was the first to declare – was sitting on 21 last night.

Tory MPs will vote tomorrow, and two candidates will be put forward to the Tory membership unless one pulls out, with a result being announced on Friday.

Analysts at Berenberg Bank said there were greater market risks from a Johnson government, with the FT reporting the bank told its clients: “Given that a majority of Conservative MPs probably do not want Johnson as their leader, the prospects of mass resignations and a further descent into chaos would loom large.”

Some MPs have warned they would resign the Tory whip and sit in the Commons as independents if Johnson returns to Downing Street.

Johnson’s potential reinstatement has divided opinion even among his allies in the parliamentary party, including his former deputy prime minister and foreign secretary Dominic Raab.

Appearing on the broadcast round yesterday morning, Raab said “we cannot go backwards” and pointed out Johnson faces a probe into his actions over partygate.

He told BBC Radio 4’s Today programme: “I stood by Boris, I’ve got a lot of respect for him. I think he can make a return to frontline politics and I like him personally.

“The challenge is this Committee on Privileges and Standards is entering a new phase, there’s going to be oral testimony from people from Number 10.

“He’s going to have to give oral testimony and I just can’t see in practice how the new prime minister, in office latest next Friday, could give the country the attention, the focus that it needs and at the same time be giving testimony and be answering all of those questions. So I don’t say it with any relish. I’m sad about that situation.

Raab added: “We cannot go backwards. We cannot have another episode of the Groundhog Day, of the soap opera of partygate. We must get the country and the Government moving forward.”

Raab backed Sunak, saying he was “very confident” he would stand and had already secured the backing of 100 MPs, shoring up sufficient support to be on the ballot for tomorrow’s vote.

He told BBC Breakfast: “I think the critical issue here is going to be the economy. Rishi had the right plan in the summer and I think it is the right plan now.”

Raab said he felt Sunak could “bring the party together with a government of all of the talents”.

Moments after Johnson landed, former home secretary Priti Patel said she would be backing him but his campaign suffered a blow as former close allies Steve Barclay and Lord Frost urged colleagues to back Sunak.

Mordaunt, the Leader of the House, who finished third in the last leadership election, said she had been encouraged by the support she had received from fellow Conservative MPs and wanted to unite the party. She also assured Jeremy Hunt he could stay on as Chancellor if she won.

There is speculationamong backers of the old Downing Street neighbours that Johnson and Sunak could strike a deal to stand together but this would need them both to bury a lot of rancour.