Andrea Leadsom said only a Brexiteer could deliver on the referendum result as she joined the race to be prime minister.
The energy minister told Sky News the next Conservative leader “has to be someone who will deliver on the promise of the referendum because they can see the huge advantages and believe in them”.
“I think it is very difficult for someone who campaigned to stay in and who thinks there will be disaster if we leave and so on to suddenly turn it around and start believing that we can make a go of it.”
Mrs Leadsom, Justice Secretary Michael Gove and ex-defence secretary Liam Fox are the pro-Leave MPs in the five-strong field – lined up against Home Secretary Theresa May and Work and Pensions Secretary Stephen Crabb.
She said she was “shocked and disappointed” that Boris Johnson had withdrawn, calling him “a really good man and a really good candidate”.
But she also defended Mr Gove – whose eleventh hour decision to abandon a proposed joint ticket with Mr Johnson and put himself forward prompted the dramatic U-turn by the ex-London mayor.
“Michael is just a brilliant person and no-one can be in any doubt that he was taking the view about what is best for the country.
“People really should accept that both Boris and Michael have given up a lot for what they see as the right thing for this country.”