However, some defended Johnson's remarks.
In the interview, Mr Baker said: "If we come out of conference with her hoping to get Chequers through on the back of Labour votes, I think the European Union negotiators would probably understand that if that were done, the Tory Party would suffer the catastrophic split which thus far we have managed to avoid".
Johnson's successor, Foreign Secretary Jeremy Hunt, wrote in a rival article in the Mail that "nobody else has a detailed plan" for Brexit, adding: "This is the moment to back the prime minister".
Britain's ruling Conservative party was locked in a new row over Brexit Sunday after Boris Johnson said the government's strategy put the country in a "suicide vest", with Brussels holding the detonator. "We look like a seven-stone weakling being comically bent out of shape by a 500-pound gorilla".
"We have wrapped a suicide vest around the British constitution - and handed the detonator to Michel Barnier".More news: Xbox introduces innovative limited edition grease-proof controller
Johnson also criticized the Northern Ireland "backstop" by assuming that the United Kingdom has given Barnier "a jimmy" with which Brussels can choose at any time "to crack apart" the union between Great Britain and Northern Ireland. It should be "the political end of Boris Johnson", Duncan wrote on Twitter. "If it isn't now, I will make sure it is later".
"There is no justification for such an outrageous, inappropriate and hurtful analogy", Minister of State for International Development Alistair Burt added.
'If we don't stop this extraordinary use of language over Brexit, our country might never heal.
"Comparing the Prime Minister to that isn't amusing".
Tory MP Sarah Wollaston said she "very much doubted" she would stay in the party if he became leader.
"When negotiating, the prime minister needs to demonstrate her intent and also her power to deliver", Mr Baker told the Press Association.More news: Luke Shaw injury: Man Utd star 'doing fine' after Carvajal collision
But other colleagues of Mr Johnson said critics were "terrified of his popular appeal" and that he "speaks truth unto power".
Last week, Johnson and his wife Marina Wheeler announced they were divorcing after 25 years of marriage - a move some saw as an attempt to neutralise potential stories about his private life before a leadership campaign.
In a sign of the febrile atmosphere within the Conservative Party, the Sunday Times reported that Mrs May's aides had drawn up a dossier on Mr Johnson at the time of the 2016 leadership contest.
Downing Street denied re-releasing the details to discredit him now.
Brexit-backing Tory Ross Thomson questioned what Number 10 was playing at and said he was "very disappointed" with the "gutter politics".More news: Eye of Hurricane Olivia breaking apart