Rishi Sunak has signalled that the door is open for Boris Johnson to hit the campaign trail for the Tories.

There has been speculation that the former prime minister, still seen by many Conservatives as a strong campaigner, might help drum up support for the party ahead of the July 4 General Election.

Mr Sunak’s Wednesday announcement of the summer polling day fuelled questions over what role his 2019 election-winning Downing Street predecessor might play in the campaign.

Asked whether it is time to bring back Mr Johnson, the Prime Minister said he would welcome “any Conservative to come and join the campaign” as he expressed pride in their time working together.

A spokesman for Mr Johnson did not comment on his plans for the campaigning period, telling the PA news agency: “Boris Johnson is, as always, strongly supporting the Conservatives and encourages everybody to do the same.”

Speaking in Belfast as part of his whirlwind campaign tour of the UK, Mr Sunak told broadcasters on Friday: “I’m very proud of the record of the Conservative Government over the last 14 years. And of course we haven’t got everything right and circumstances have been difficult, but there’s an enormous amount to be proud of.

“And when it comes to Boris he was of course the person who got Brexit done, ensured we had the fastest vaccine rollout in Europe and was the first to make sure that we provided support to Ukraine.

“And I think all Conservatives will want to join the campaign because all Conservatives are united in wanting to see a Conservative government at the next election, because it’s the Conservatives that have got a clear plan that we’re working towards.”

He added: “I’m very proud of the work that we did together.”

Mr Johnson entered the election fray on Friday evening, using his first Daily Mail column since the vote was called to attack Sir Keir Starmer.

In a sign he will not remain silent in the run-up, Mr Johnson claimed the Labour leader would be the “most dangerous and left-wing prime minister since the 1970s” and that the Opposition would not maintain its hefty poll lead as election day approached.