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Voters do not know if David Cameron is a “toff with a conscience” or whether he can relate to wider society, according to a vice-chairman of the Conservative Party.

Kulveer Ranger, promoted to Conservative headquarters last month, also believes that Mr Cameron’s “aristocratic tinge” is his “Achilles heel”.

His remarks emerged as the Tory leader launched a proposal to mix wealthy school leavers with teens from poorer backgrounds in a modern version of national service.

Mr Cameron, setting out his proposals in a newspaper interview, took a sideswipe at those like Michael Ancram, who claimed that the Tory leader was “trashing” the party’s past. Dismissing the former party chairman as a “blast from the past”, Mr Cameron warned Tories to think carefully before opening their mouths.

It was two modernisers who embarrassed him yesterday, however, as first Mr Ranger and then Michael Portillo appeared to question his leadership.

The interventions threatened to overshadow the launch of proposals to send up to 650,000 school leavers a year on six-week camps to prepare them for adulthood. They could chose to dodge their “national citizenship service” but would miss out on cash awards to help fund gap years or other forms of personal development.

Launching the scheme in Bolton, Mr Cameron said that the country needed a scheme that would mix people from different backgrounds. He said: “It will be a way of learning respect for our country and each other. just like national service was.”

Mr Cameron will be deeply irritated to see his own Old Etonian background highlighted by Mr Ranger, a 31-year-old Sikh and former Tory candidate promoted to vice-chairman for cities, in the magazine of the Conservative Way Forward group.

Mr Ranger wrote: “The aristocratic tinge to his heritage, the Bullingdon Club photo . . . reinforce all the old brand associations of a Conservative toff – albeit a modern-day toff. This is his Achilles heel.” Mr Cameron must “establish who he is. A toff with a conscience? A modern day visionary who can relate to wider society? Is he, or can he be, just like us?”

Contacted by The Times, Mr Ranger said that he was a strong supporter of the Tory leader. Meanwhile, Mr Portillo is reported to have questioned Mr Cameron’s effectiveness in modernising the party in a speech to the Marketing Forum in Southampton. Marketing Weekquoted him as saying: “To change, you need to change the people at the heart of the party. He is trying, but it has not been as successful as he hoped.”

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