A group of Liberal supporters has launched an advertising campaign against the party’s plan to build taxpayer-funded nuclear power plants, arguing it “betrays Liberal values”, divides the party and “hands government back to Labor”.

The new advocacy group Liberals Against Nuclear says it rejects the Coalition’s policy as it would require the government to borrow tens of billions of dollars, swell the bureaucracy and impose “massive taxpayer-backed risk”.

Peter Dutton’s proposal would involve eventually building nuclear reactors at seven sites across the country, mostly after 2040. In the short term, the Coalition says it would slow the rollout of renewable energy, attempt to extend the life of ageing coal-fired power plants and rely more on gas-fired power.

The Liberals Against Nuclear spokesman is Andrew Gregson, a former Tasmanian Liberal director and candidate who said he was not currently a party member but remained a supporter. He declined to say how many supporters the group had or name other members, but said those involved were concerned the nuclear policy was driving “free market and middle ground voters” to support “teal” and other independent MPs in seats the Coalition must win to return to government.

“We’re trying to save the party from a policy that will gift seats to their opponents,” he said. “Nuclear technology itself isn’t the issue. It’s the socialist implementation being proposed that trashes Liberal values.

“If nuclear energy is so good then the market will back it without massive government intervention.”

The group is running television, digital and billboard ads that argue “many Liberals are against nuclear”. One of the ads shows a woman reading a newspaper article that quotes the Nationals senator Matt Canavan as saying “nuclear fixes a political issue for us but ain’t the cheapest form of power” and cites a report by the Institute for Energy Economics and Financial Analysis that found the Coalition proposal would lead to a $665 increase in average power bills. The ads ask the opposition leader, Peter Dutton, to “please dump nuclear”.

Gregson said they would run across the country and be particularly targeted in marginal seats, including those held by teal MPs. He said the ads were aimed at the party, not voters.

Liberals Against Nuclear said polling had suggested only 35% of Australians backed nuclear energy, and that support collapsed once voters understood the policy details. Its website raises concerns about the policy driving up national debt and creating safety and security risks.

Gregson said dropping the policy would cause the Coalition a “couple of days’ worth of negative publicity” but would not cost it the election. “Nuclear power is the big roadblock preventing the Liberals getting to The Lodge,” he said.

Asked about the campaign on the Seven Network, Dutton said his policy was “based on the international experience” and claimed it would bring electricity costs down by 44% and provide “stability in the market”.

The Climate Change Authority, a government agency, found the Coalition’s proposal would add an extra 2bn tonnes of carbon dioxide to the atmosphere and make it “virtually impossible” for Australia to reach net zero by 2050, a position the opposition claims to support.

Labor has a target of 82% of generation coming from renewable energy by 2030, up from the current level of nearly 45%. The authority said that under the Coalition’s plan there would probably not be 82% of electricity from zero emissions technology – renewables and nuclear – until 2042.

Independent experts have suggested the Coalition policy would likely lead to household power bills being higher than under Labor’s policy as there would be less generating capacity competing in the grid. They have also said it would increase the risk of the electricity supply becoming unreliable at peak times as it was more reliant on old coal power plants that are nearing the end of their expected operating lives.