In highly personal remarks, the mother-of-three said she was sure the Home Secretary must be "really sad" not to have children as she suggested that her motherhood status meant she had more invested in the future than her leadership rival.

"Genuinely I feel that being a mum means you have a very real stake in the future of our country," Ms Leadsom told The Times in an interview.

She went onto say Ms May "possibly has nieces, nephews, lots of people. But I have children who are going to have children who will be directly party of what happens next."  

Her remarks come just days after the British Home Secretary spoke for the first time about the sadness she and her husband Phillip felt when they discovered they couldn't have children.

"Of course, we were both affected by it," Mrs May told the Mail on Sunday. 

"You see friends who now have grown-up children, but you accept the hand that life deals you. Sometimes things you wish had happened don't or there are things you wish you'd been able to do, but can't. There are couples in a similar position."

Mrs May revealed in the interview she and her husband of 35 years did seek expert advice in a bid to become parents - but it never happened.

Asked whether she felt it had affected her outlook as a politician she said, "I don't think so, it's an impossible question because you can't tell what you'd have been like if you'd been in a different position."

Theresa May: clear favourite

The two women are going head-to-head to win the Conservative leadership race and become the next Prime Minister after Michael Gove, the British Justice Secretary, was knocked out of the ballot of MPs on Thursday, picking up just 46 votes, against 84 for Mrs Leadsom and 199 for Mrs May.

While Mrs May is the firm favourite among MPs to become their next leader, Mrs Leadsom's supporters believe her credentials as a campaigning Brexiteer on the right of the party could garner plenty of support among grassroots members.

Mrs Leadsom said her big family and kids are "a huge part of my life" and help her to connect more with other people.

"I think when you're thinking about the issues that other people have you worry about your kids' exam results, what direction their careers are taking, what we are going to eat on Sundays."

The 53-year-old said she was sure that Mrs May's lack of children was difficult for her. "I am sure Theresa will be really sad she doesn't have children so I don't want this to be 'Andrea has children, Theresa hasn't, because I think that would be really horrible." 

But she also reiterated the difference she thinks being a mother would make should she become Prime Minister.

"It means you don't want a downturn but, never mind, 10 years hence it will all be fine. My children will be starting their lives in the next 10 years, so I have a real stake in the next year, next two."

Before the interview was released, Mrs May had issued a statement imploring her opponent to a fight a clean campaign and stay within the "acceptable limits" of political debate, in an acknowledgement of rancour shown on both sides during the EU referendum campaign.

One MP backing Mrs May told The Times the comments were "disgusting".

"I think it is going to insult a lot of Conservative activists as well as a lot of nice, decent people."