Boris Johnson will continue to “throw rocks” at Theresa May’s Chequers plan in the weeks running up to Tory conference but has no plans to launch an immediate leadership bid amid the fallout from his personal life, his close allies have claimed.

Sources close to the former foreign secretary said his primary focus was on persuading the prime minister to drop her plans in favour of a free-trade agreement, although they did not deny that his ultimate ambition remained to take over at No 10.

The Conservative party erupted into open civil war at the weekend after Johnson described May’s Brexit plan as a “suicide vest” for the UK, prompting claims he was attempting to draw attention away from the breakdown of his marriage.

Furious Brexiters claimed that Johnson was being targeted by a smear campaign orchestrated by Downing Street, which No 10 has denied – but the schism heralded a turbulent run-up to the party’s conference later this month.

The pro-Brexit campaign against the Chequers plan, led by the Eurosceptic European Research Group, appeared to have stalled on Monday amid uncertainty over when they would publish their long-awaited alternative proposals.

One friend of Johnson said: “Is he going to lead the ERG and depose her now? The answer is no. His plan is still to show what he believes are the failings of Chequers and get her to change her mind and revert to Lancaster House.

“Yes, he’s talking to them but he doesn’t want to be fronting any leadership challenge, that’s not what he’s interested in. He’s interested in changing the policy, not the prime minister. Everyone knows he eventually wants to try to become leader. But not now.”

Johnson plans to use his newspaper column in the run-up to Tory conference to persuade May to change her mind. In her Lancaster House speech in January 2017, she proposed a “comprehensive, bold and ambitious” free-trade deal with the EU.

The ex-foreign secretary is no longer thought to be in direct contact with the prime minister, although his lunch meeting with chief whip Julian Smith last week raised speculation that the channels of communication remained open.

The MP is planning to spend only one day at conference, where he is due to address a “chuck Chequers” rally of as many as 1,000 Tory activists. He is understood to have turned down at least one request for a high-profile broadcast interview.

A second ally said: “He will continue to throw rocks at Chequers because he thinks she should be changing direction. He’s not chucking them at the PM. Like all the anti-Chequers voices, he thinks she should go back to the original version of Lancaster House, which was supported by a broader section of the Conservative party.”

There were also allegations at the weekend that a dossier about Johnson’s personal life, created by a member of May’s 2016 leadership campaign team, had recently been circulating in Westminster. The Johnson camp believes that No 10 and CCHQ had been planning to “build on it” in recent days.

However, Downing Street denied any involvement in the creation or circulation of any dossier. “Any involvement of No 10 is categorically untrue and offensive,” the prime minister’s official spokesman said.

Reports of Johnson’s relationship with Carrie Symonds, the Tory party’s former head of communications, dominated the weekend papers but those close to him said the turbulence would not distract him from his attacks on Chequers. “He will not be deflected,” one said.

They also rejected claims that he had been “clearing the decks” by announcing his divorce before a potential leadership bid. “For Marina [Wheeler] the timing is not a priority, it’s entirely understandable that she just wants to get on with it.”

The MP and his barrister wife, with whom he has four children, are understood to have decided to split earlier this summer while he was still foreign secretary. She is expected to lay divorce papers this week.

No 10 was understood to be inviting backbenchers to dinners this week ahead of a crunch cabinet meeting on Thursday to discuss no-deal preparations. Brexit secretary Dominic Raab will publish the second set of no-deal papers straight afterwards.

Former Brexit minister Steve Baker, who quit in July over Chequers, said the Conservatives would face a catastrophic split if May relied on Labour votes to push her proposals through parliament.

He said at least 80 Conservative MPs would be willing to vote against the plan, which Eurosceptics argue ties the UK too closely to the EU on regulation and alignment, which they believe would hamper future trade deals. Tory insiders said the figure was optimistic.

Baker batted away questions over when the ERG would publish its alternative plan. “We’re not the government. It’s not our job to dictate policy, we wish to make helpful suggestions. We’re going to focus down on one or two key issues and we’re not going to allow ourselves to be driven by the overwhelming interest in our ideas,” he said.

It came as Brexiters claimed on Monday that the independent constituency boundary review had “raised suspicions” because leading Eurosceptics including Johnson, David Davis, Priti Patel and Iain Duncan Smith all faced losing their seats.

“There’s a general consensus that the party are more concerned about ridding itself of opposition to Chequers and difficult Eurosceptics than it is in keeping the seats at the next general election. It raises suspicions of a concerted campaign,” one said.