Boris Johnson has more than 100 backers and, therefore, could be on the leadership ballot, a source has told Sky News.
The news comes as speculation mounts that the former prime minister will enter the Tory leadership race.
Mr Johnson has been on holiday in the Dominican Republic but flew home after Liz Truss’s dramatic resignation on Thursday.
The Conservative Party has a week to pick a new leader and prime minister, with Mr Johnson telling an ally he was “up for it” and “I’m going to do it”.
‘Difficult to see’ how Johnson could be PM – politics latest
Mr Johnson flew to Gatwick Airport in economy alongside his wife and children and there was “mixed reaction” as he and his family boarded the plane before everyone else, according to Sky’s US correspondent Mark Stone.
He said several passengers looked “slightly bewildered” and there were a few boos.
The flight was tracked by around 7,000 people through the FlightRadar24 website.
Mr Johnson waved to the press after he landed at Gatwick Airport and was ushered quickly through the VIP terminal by security.
He was then taken to a Range Rover, which took him away from the airport.
Mr Johnson officially resigned six weeks ago after a series of scandals and mass resignations by ministers but is still popular among some Tory MPs and the party membership.
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Who are Tory MPs backing to be the next prime minister?
Six cabinet ministers have said they would back Mr Johnson in the contest.
Earlier backers include Jacob Rees-Mogg, the business secretary, Ben Wallace, the defence secretary, and Simon Clarke, the levelling up secretary.
Mr Rees-Mogg was the first to declare himself for the former prime minister, posting on social media: “I’m backing Boris #BorisorBust.”
After ruling himself out of the race, Mr Wallace said he is “leaning towards Boris Johnson”.
He warned that colleagues “have to focus” on who will bring unity and be able to win the next election.
Former home secretary Priti Patel said she was backing Mr Johnson because he has a “proven track record”.
Tory MPs wishing to enter the race must secure the backing of 100 MPs by 2pm on Monday.
Mr Johnson remains a divisive figure, however, and some Conservative MPs have threatened to withdraw the party whip if he returns.
Lord Frost, a former Brexit minister and close ally of Mr Johnson, called on his party colleagues to back Rishi Sunak, the former chancellor.
Jesse Norman, the Foreign Office minister, said selecting Mr Johnson as Conservative leader would be “absolutely catastrophic”.
Sir Roger Gale, the senior backbencher, reminded voters in a tweet that the former prime minister remains under investigation by the Commons privileges committee for potentially misleading the House over partygate.
Sir Roger told Times Radio that, if Mr Johnson is voted back in as prime minister, he would give up the whip and stand as an independent.
Asked about Mr Johnson’s chances at a second run for office, one cabinet minister told Beth Rigby, Sky News’ political editor: “I’d expect him to get to 100.
“Even people who resigned from his government were on the terrace yesterday telling colleagues they would now back him and members definitely will.”
A friend of Mr Johnson also told Sky News it is “likely” he will stand.