The Conservatives will face “challenging” circumstances in upcoming by-elections, the prime minister has said. 

Rishi Sunak warned that “mid-term by-elections for incumbent governments are always difficult”, as he faced questions from reporters during the NATO summit in Lithuania.

During the exchanges, it was pointed out to Mr Sunak that, if he loses all three scheduled by-elections, it would represent the worst performance from a governing party in half a century.

July 20 will see elections in London’s Uxbridge South Ruislip following the resignation of Boris Johnson and in Selby and Ainsty after his ally Nigel Adams quit. 

A third will take place in Somerton and Frome in Somerset, triggered by the resignation of David Warburton. Nadine Dorries, MP for Mid Bedfordshire, has also announced her intention to quit but has not formally moved to do so. 

Asked if he would resign if he loses all three scheduled by-elections, Mr Sunak replied: “Look — mid-term by-elections for incumbent governments are always difficult. That’s not news to anybody. Clearly the circumstances for these by elections are obviously challenging.”

He insisted that when campaigning in Selby, he saw “great energy and enthusiasm from volunteers and members”, and claimed voters want him to focus on his five priorities.

“Whether that’s getting inflation under control, halving it, whether that’s tackling NHS waiting lists, stopping the boats … and local issues … putting more police officers on the streets, tackling rural crime, which is what exactly we’re doing”, he said. 

Mr Sunak visited Selby last week as his party fights to retain the seat won in 2019 with a 20,000 majority.

The prime minister he added: “Of course, I know things are tough — I can see that, I talk to people about it every week. I always knew it was going to take some time to improve things. But it doesn’t mean the course we’re on is the wrong one. Just because it takes time and is difficult.

“When I set those priorities — I didn’t set them because they were easy, I set them because I was ambitious for the country. They are the right things to focus on.”