Backing Boris Johnson to become the next prime minister would have been a "betrayal" of the country - said PM hopeful Michael Gove.
The Justice Secretary, who worked closely with Johnson before announcing his own bid for leadership, suggested that politics is not the place to put friendship first and said London's former mayor "ducked" crucial decisions and failed to show the qualities needed to take over from David Cameron.
He told BBC One's Andrew Marr show: "I've taken some difficult decisions, but I've always taken those because I've put my country and my principles first."
Gove said he took the decision "very late" on Wednesday evening after talking to close colleagues and wife Sarah Vine and said he had "tried" to ring Johnson to tell him about the decision. But, he said, "the clock was ticking" in the leadership contest.
Explaining his side of the story and how he came to a "reluctant" decision, he said: "Right until the 11th hour I was talking to parliamentary colleagues, friends seeking to persuade them that Boris could lead the country and could be prime minister but in the final 24 hours there were actions that were taken, decisions that were ducked that led me to believe...
"I knew that by taking that decision all sorts of people would attack me personally but I love my country, I could not recommend that Boris was prime minister, I had tried to make that work and, therefore, it would have been a genuine betrayal of principal and of this country to have allowed Boris's candidacy to go ahead with my support."
He said that, while he had "enjoyed" working with Johnson during the referendum campaign, the former mayor - who has often been labelled as "bumbling" - lacked "grit, executive authority, sense of purpose, clarity".
His words came in response to fierce criticism mentioned by Marr, who told Gove he was viewed as the "Frank Underwood" - the Machiavellian character from the US version of House of Cards - of British politics and had "betrayed" his friends.
But Gove said putting friendship first in politics did not serve the country.
The writer of House of Cards himself, Michael Dobbs, a former deputy chairman of the Conservative party, criticised the way the leadership contest was developing - comparing it to a "posh boys' punch up".
He told Radio 4´s The World This Weekend: "This is serious stuff. We are talking about the future of the country, the future of Europe and somehow it's been reduced to not House of Cards, more like St Trinian's.
"It's like a posh boys' punch up and frankly, I and millions of people around the country are rather fed up with it."