Johnson’s team claims he has the numbers to get on the ballot paper

Boris Johnson’s campaign team has told supporters they have secured the nominations needed from MPs for him to get on the ballot paper in the race for No 10, it has been reported.

The former prime minister has yet to declare whether he is standing – and the number of MPs publicly declaring for him is still well below the 100 needed.

However, Northern Ireland Secretary Chris Heaton-Harris has sent a Whatsapp message to supporters claiming they have the numbers, according to the The Sun’s political editor Harry Cole.

Mr Heaton-Harris told them: “OK everyone! Some very good news! Thanks to all your hard work I can confirm we have completed all the paperwork (verified all nominations, with proposer and seconder) to be on the ballot tomorrow.”

However, supporters of former chancellor Rishi Sunak reacted to the claim with suspicion, suggesting it was a desperate attempt to drum up support.

Backbencher Richard Holden tweeted: “Very odd to brief this out again… (two days in a row). It’s what they briefed yesterday.

“It’s almost as if they still need people and are desperate to show momentum, which they can’t because no-one will publicly come out.”

Under the leadership rules candidates have until 2pm on Monday to get the necessary nominations.

Earlier, Mr Sunak became the second contender formally to declare he is standing, promising to “fix our economy, unite our party and deliver for our country” at a time of “profound economic crisis”.

The former chancellor already has more than 140 MPs publicly backing him, according to some reports, meaning his place on the ballot paper should be secure.

Meanwhile, allies of Penny Mordaunt – who was the first candidate to declare – have disclosed that she has been speaking to Mr Johnson.

The PA news agency understands that he asked her to stand aside and back his campaign, but she refused, saying most of her supporters would switch to Mr Sunak if she pulled out.

The disclosure, however, fuelled speculation that Mr Johnson has been struggling to get the numbers he needs.

His supporters have suggested that the shortfall in public declarations was in part due to the fact that some MPs backing him were reluctant to go public until they are certain he is standing.

While Mr Sunak remains the favourite to top the ballot of MPs, Mr Johnson’s supporters believe can win the final online poll of ordinary party members which will decide the contest.

It raises the prospect of another scenario – as with Liz Truss – where the choice of the activists does not have the backing of MPs potentially leading to more turmoil and division at Westminster.

Northern Ireland Minister Steve Baker warned Mr Johnson – who still faces a Commons inquiry into whether he misled Parliament over lockdown parties in Downing Street – would be a “guaranteed disaster.

“There’s going to be a vote before the House of Commons on this issue of privileges, whether he deliberately misled the House,” he told Sky News’s Sophy Ridge on Sunday.

“In that vote it’s guaranteed there’ll be a large number of Conservatives who will refuse, as they see it, to lay down their integrity to save him, and at that moment his premiership will collapse.”

Mr Baker, an ardent Brexiteer, was one of two senior figures on the right along with former home secretary Suella Braverman to declare for Mr Sunak.

The former chancellor also picked up endorsements from cabinet ministers Grant Shapps, Chloe Smith and Michelle Donelan.

Announcing his candidacy on social media, Mr Sunak said he had a “track record of delivery” and a clear plan to steer the economy through “the toughest of times”.

“There will be integrity, professionalism and accountability at every level of the government I lead and I will work day in and day out to get the job done,” he said.

Meanwhile, Mr Johnson gained the backing of Foreign Secretary James Cleverly and Nadhim Zahawi, the Chancellor of the Duchy of Lancaster.

Mr Zahawi said the ex-prime minister “got the big calls right” and argued “Britain needs him back”.

He tweeted: “When I was chancellor, I saw a preview of what Boris 2.0 would look like. He was contrite and honest about his mistakes. He’d learned from those mistakes how he could run No 10 and the country better.”

Despite trailing in the public declarations, with fewer than 30 MPs openly supporting her, Ms Mordaunt, the Leader of the House, insisted she was not out of the race.

“I’m in this to win it. I think it’s important for our party we have a contest. I am very confident about our numbers,” she told the BBC’s Sunday With Laura Kuenssberg programme.