Jeremy Hunt has stepped up his criticism of Boris Johnson for avoiding media scrutiny in the Tory leadership campaign, calling it “disrespectful”, as another minister said Johnson could be brought down by his own MPs if he pushed for a no-deal Brexit.

Tobias Ellwood, the junior defence minister, said it was possible that the decision by Johnson actively to seek no deal could push some Conservatives to support a no-confidence motion against his government.

“I believe that absolutely is the case,” Ellwood told the BBC. “I think a dozen or so members of parliament would be on our side, would be voting against supporting a no deal and that would include ministers as well as backbenchers.”

Following a hugely difficult weekend for the Johnson campaign, dominated by questions about why police were called to his home after an argument with his partner, Carrie Symonds, allies of the former foreign secretary sought to fight his corner.

Matt Hancock, the health secretary, who supported Johnson after abandoning his own leadership bid, said it was “nonsense” to accuse the frontrunner of avoiding scrutiny, saying he was taking part in dozens of Conservative hustings events.

Priti Patel, the former international development secretary and another leading Johnson supporter, told the BBC that Johnson was facing “a very clear, politically motivated series of attacks” over the incident on Thursday night at the London home he shares with Symonds.

Johnson has refused to comment on the circumstances of a furious row that led one neighbour to record some of the shouting from inside his flat, and informed the Guardian about the incident. Other neighbours said they had considered calling police.

“The very prospect of someone taping someone in their private home, frankly, tells me that is politically motivated,” Patel said. “And that is not the type of behaviour that you would expect in our country. It’s the type of behaviour associated with the old Eastern Bloc.”

Profile Boris Johnson's Tory leadership campaign Show Personal style A late-night altercation between Tory leadership favourite, Boris Johnson, and his partner, Carrie Symonds initially changed the dynamics of Johnson's campaign. He had been either invisible or deliberately sober to the point of dullness, when his usual primary draw to Tory members is a self-created sense of optimism and fun. Much is also made of his supposed broad appeal to the electorate, evidenced by two terms as London mayor. His bizarre claim to make model cardboard buses has raised eyebrows. In most political contests, Johnson’s character – he has lost more than one job for lying, and has a complex and opaque personal life – would be a big issue, but among the Tory faithful he seemingly receives a free pass. It remains to be seen what impact that late-night police visit will have on his chances. Brexit He has promised to push for a new deal while insisting the UK will leave the EU come what may on 31 October, even if it involves no deal. While his hard Brexit supporters are adamant this is a cast-iron guarantee of leaving on that date, elsewhere Johnson has been somewhat less definitive. Asked about the date in a BBC TV debate, Johnson said only that it was 'eminently feasible', although he then went on to tell TalkRadio that the 31 October deadline was 'do or die'. Taxation His main pledge has been to raise the threshold for the 40% higher tax rate from £50,000 to £80,000, at a cost of almost £10bn a year, which would help about 3 million higher earners, a demographic with a fairly sizeable crossover into Tory members. Johnson’s camp insist it would be part of a wider – and so far unknown – package of tax changes. Public spending He has said relatively little, beyond promising a fairly small increase in schools funding, as well as talking about the need to roll out fast broadband across the country. Johnson has generally hinted he would loosen the purse strings, but given his prior fondness for big-ticket projects – London’s cancelled garden bridge, the mooted 'Boris island' airport – perhaps expect more of a focus on infrastructure projects than services. Climate and environment This is unlikely to be a big issue for Conservative party members, and Johnson has not said much on this beyond confirming his general support for the new government target of cutting greenhouse gas emissions to a net zero by 2050. Foreign policy Also unlikely to be a big issue among Tory members, beyond vague platitudes on 'global Britain', it could be a weak spot for Johnson given his poor performance as foreign secretary. He was seen as something of a joke by diplomats – both UK and foreign – and is likely to face more questioning over his gaffe about the jailed British-Iranian woman Nazanin Zaghari-Ratcliffe Peter Walker Political correspondent Photograph: Isabel Infantes/AFP

Patel said such incidents were “very much there to deflect upon the fact he is a Brexit candidate”. She said: “Quite frankly this has now become very much, I think, remain versus leave, and a personal attack and campaign against Boris.”

Speaking earlier to Sky News, Hunt declined to comment on the incident with Symonds, saying only: “He’s got to decide what he says about his private life.”

But Hunt was scathing about Johnson’s decision to avoid almost all media interviews and debates, calling it “very disrespectful to Conservative party members”.

Johnson has agreed to take part in an ITV event on 9 July, by which point party members will have received their ballots. But he is avoiding a planned Sky debate on Tuesday.

“I’m saying that it is cowardice, frankly, not to appear in head-to-head debates against me,” Hunt said.

“You can’t become prime minister without answering questions about the decisions you’re going to have to take almost immediately you get through the door of No 10. My worry is that Boris has got a coalition of people like Matt Hancock, who want no deal taken off the table, and Mark Francois, who wants no deal – that coalition will dissolve very, very quickly indeed when he has to take some actual decisions.

“Sometimes in politics you can fudge, but on Brexit you can’t. There are going to have to be decisions, and that’s why it’s very important that the new prime minister has a mandate from having spelled out exactly what they’re going to do.”

Hunt also accused Johnson of appearing willing to “slink through the back door” of No 10 by “pathetically” evading questioning. “Don’t be a coward, Boris, man up,” he wrote in Monday’s edition of the Times.

Warnings such as those from Ellwood about no-confidence motions made proper scrutiny all the more necessary, Hunt argued: “In that situation, is he going to have an election in order to get a majority in parliament for a no-deal Brexit? I think Conservative party members need to know the answer to those questions.”

Defending Johnson on BBC1’s Breakfast, Hancock said the dozen-plus party hustings and other events amounted to “endless and constant scrutiny”.

Hancock added: “Of course, the question of whether Boris’s private life is private is, perfectly reasonably, up to him. I don’t think anybody would like their conversations late at night to be listened in to and snooped on by a neighbour.”