Mrs Cameron used an interview with the Sun to give an insight into her life with the Prime Minister at Downing Street, and praise the way he handles the pressure of the job.
But she played down suggestions that David turns to her for advice on key decisions, saying she was “fairly hands off” with politics.
The intervention came after the Labour leader’s wife, Justine, gave a rare on-screen interview, arguing that her husband stood for “decency and principle”.
“I think over the next couple of months it’s going to get really vicious, really personal, but I’m totally up for this fight,” Mrs Miliband said.
Mrs Cameron – once described by former Tory spin doctor Andy Coulson as the PM’s “best weapon” – said he was a “brilliant dad and a brilliant husband”.
“I am proud of my husband all the time. It’s such a stressful job with a huge amount of responsibility and he does deal with it really well,” she said. “He has an amazing ability to stay calm, he’s very level-headed. He tends to operate quite well under pressure.
“For me, what’s brilliant is he can do that and still be a brilliant dad and a brilliant husband. I’m very grateful for that.”
Mr Cameron previously said he spoke to his wife about “life and death decisions” including hostage rescues and troop deployment but Mrs Cameron said: “I don’t know what he was thinking of.”
The 43-year-old added: “I’m a fairly hands-off political wife. I don’t get involved in the machinations at all. I don’t think he takes my advice about politics. I wouldn’t want him to, it would be too much responsibility for me.
“We talk about stuff when he gets upstairs, I listen to the radio a lot. As with any husband and wife you get the view of a mum.”
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