The government is not trusted by a majority of voters to protect the BBC during the forthcoming renewal of its charter, according to a poll that shows most people view the corporation as the most impartial and reliable news broadcaster in the UK.

A YouGov survey for the campaigning organisation 38 Degrees found that distrust of the government about its BBC reform plans is strongest among those aged over 60, the group most likely to be Tory supporters.

The poll, the first of its kind to look at attitudes to the BBC among older voters, found that 62% of over-60s are suspicious of government intentions, more than double the 27% who say they have faith in ministers to make the right decisions. The findings will raise increasing doubts among many Tory MPs about the political wisdom of meddling with an organisation seen by many of the party’s voters as a cherished part of British life.

Of all those questioned, 61% said the quality of the British media would deteriorate if commercial advertising were introduced on the BBC, against just 8% who think it would bring improvements.

Culture secretary John Whittingdale wants to abolish the BBC Trust and give the government power to appointa new unitary board. Photograph: Peter Byrne/PA

In March culture secretary John Whittingdale announced plans to give the government power to appoint most of the members of a powerful new board that would run the BBC, sparking heated debate about whether the corporation could remain independent of political control. Whittingdale wants to abolish the BBC Trust, the corporation’s governing body, and create a new unitary board with responsibility for the broadcaster’s day-to-day operations – a suggestion strongly opposed by many at the BBC.

There have also been reports that Whittingdale is looking at plans that would mean the BBC having to hand some of the public money raised from the licence fee to other broadcasters to fund some of their programming as part of a radical reform agenda.

David Babbs, executive director at 38 Degrees, which is heading a campaign to protect the BBC, said: “The BBC is a national treasure. But its future is at risk. Any government that damages the BBC will be on the wrong side of the British public. John Whittingdale’s proposed reforms are going down like a lead balloon with key groups of target voters.”

Among all voters, the poll found 53% do not trust the government with the future of BBC news, local radio and coverage of sporting events. When asked which broadcasting organisation they thought was most likely to produce balanced and unbiased news reporting, 56% put the BBC first against 14% for ITN News, 13% for Sky News and 13% for Channel 4 News.

Labour has recently accused ministers of trying to “intimidate” the BBC as part of a wider attempt to limit scrutiny of its activities. Shadow culture secretary Maria Eagle said that its changes to the BBC should be viewed alongside plans to cut Labour party funding, weaken trade unions and curtail the policy work of charities as proof that the Tory party was “committed to trying to ensure it wins the next election by skewing the political landscape for their own party political advantage”.

Ministers have suggested that a long-awaited white paper on the future of the BBC will be delayed until after the referendum on the UK’s membership of the EU on 23 June. The current BBC charter is due to expire at the end of this year but could be extended.

Whittingdale has previously denied that his review of the BBC is ideologically driven. “I’m a huge admirer of the BBC. But every 10 years the BBC’s charter expires and that’s the right time that we should look at what the BBC does, how it’s financed, how it’s governed, and consider whether or not changes should be made,” he said last year.