David Cameron's mother and aunt have condemned council spending cuts that would see the loss of every children's centre in his constituency.
His mother, retired magistrate Mary Cameron, 81, has signed a petition calling for 44 children's centres due to be closed by Conservative-run Oxfordshire County Council to be saved.
Council workers in Mr Cameron's Witney constituency will stage a 24-hour strike next week in protest at the plans, with the union Unite accusing the council of "turning its back" on children, young people and their families.
Meanwhile his aunt, Clare Currie, spoke out against the proposals, branding them a "great, great error", but saying that Mr Cameron does not want the centres shut either because "he's a family man too".
Mrs Cameron, her sister, apparently signed the petition while she was visiting her son. She told the Daily Mirror: "My name is on the petition but I don't want to discuss this any further."
Ms Currie told ITV News the council should "refuse" to make the cuts, which she called a "very short-sighted decision", pleading with her nephew for money to keep the centres open.
She said: "I know that he (Mr Cameron) doesn't want them to be shut either. He's a family man too but they are just making such an error in taking the money away."
Asked if she felt her relationship with the Prime Minister could force a change in the council's stance, she said: "Well let's hope that it makes a difference but I doubt it will."
She added: "I think the cuts are a great, great error. Please give us enough money to keep these important things open."
Mr Cameron's official spokeswoman declined to say whether he had spoken with his mother about the anti-cuts petition.
The plans will see £8 million shaved from its children's services provision, halving the budget for early years education.
The closed centres will be replaced with eight children and family centres, but these would only be accessible to the most vulnerable people by referral, campaigners said.
Jill Huish, from the Save Oxfordshire Children's Centres campaign, told the Banburyshire Info website: "I am delighted that Mary Cameron has joined the senior voices, including that of her son the Prime Minister, against the Conservative county council's closure of children's centres.
"It seems to be a bizarre situation where David Cameron is unable to defend children's centres against the cruel cuts he's allowed his own Government to impose on local authorities."
The Prime Minister wrote to the local authority in his capacity as MP for Witney last year expressing "disappointment" at planned cuts to museums, libraries and day centres for the elderly.
But council leader Ian Hudspeth hit back, saying the curbs were the result of reductions in funding from central Government.
Mr Cameron's spokeswoman said: "The Prime Minister has talked many times about the need, as we look at how we manage our public finances better, to make sure we are making efficiencies through back office savings and therefore continue to protect the frontline and the services that local people need.
"That is something he reiterated in a letter to the leader of Oxfordshire County Council."
In response to Mr Cameron's letter, Mr Hudspeth pointed out in November that the council had already made "significant" savings totalling £626 million since 2010/11, including taking out "as much from the back office as possible".
In a letter to the PM he said the Government had cut Oxfordshire's revenue support grant by almost 50% over five years while imposing additional duties on the authority.
Oxfordshire County Council and Mr Hudspeth refused to comment on Tuesday on Mrs Cameron's signing of the petition or the planned cuts.
Unite accused Mr Cameron of being "two-faced" over his criticism of the council.
The petition, which has attracted almost 7,500 signatures, says: "Our children's centres are a lifeline to new parents who rely on locally accessible advice and support at a time when it is most needed. Cutting these essential services would leave families vulnerable and isolated, and fail an entire generation of children."