The Queensland and Victorian governments will be hit with a new television advertising campaign in an effort to persuade them to torpedo the national energy guarantee at a critical meeting in early August.

The activist group GetUp has combined with Greenpeace to bankroll what it describes as hard-hitting television advertisements targeting the two Labor-held states ahead of a meeting of energy ministers in August that will make or break the Turnbull government’s signature energy policy.

Opponents of the national energy guarantee have been frustrated that the Victorian government thus far has been muted in its public criticism of the scheme, and fear the Australian Capital Territory – which has been persistently critical – won’t sink the Neg at the Coag energy council unless one of the larger states is also on board.

With the Queensland energy minister, Anthony Lynham, calling in key stakeholders on Thursday to take soundings on the policy, GetUp’s national director, Paul Oosting, told Guardian Australia the activist group “expects all states to use their veto power” in August and fight for a national energy policy that would cut pollution and assist the transition to renewables.

The Australian Conservation Foundation echoed GetUp’s stance, declaring the current policy “unsupportable” because the emissions reduction target is insufficient to see Australia meet its commitments under the Paris agreement, and the policy as drafted makes it difficult to adjust the level of ambition.

The ACF’s Gavan McFadzean said: “What every state and territory government needs to understand is that if they sign up to this Neg, they own it and its woefully inadequate 26% pollution reduction target, locked in to 2030.

“It won’t be just Malcolm Turnbull’s Neg, or Tony Abbott’s, but Daniel Andrews’ and Annastacia Palaszczuk’s as well.”

The Turnbull government needs the backing of states that are in the national electricity market to implement the Neg, with any one jurisdiction possessing the power to kill the scheme.

Business groups have lined up in support of the Neg, urging a truce in the decade-long toxic political battle over climate and energy policy. They want a settled policy mechanism to give energy market participants certainty to invest.

Privately, some business stakeholders would also be relaxed about the commonwealth legislating a scheme that would make ramping up the level of ambition in the emissions reduction target easier to achieve – understanding that could help get the Labor states over the line on the mechanism.

But adding that flexibility could sink the policy when it returns for consideration by the Coalition party room, assuming the states don’t end it first.

The energy policy fight has been complicated in recent weeks by a renewed push by some Nationals and conservative Liberals to make ongoing support for coal part of the quid pro quo for supporting the Neg.

The states are also processing a new report this week from the Australian Competition and Consumer Commission, which recommended major changes to the electricity market, including the commonwealth underwriting new generation projects in order to get more competition into the system and lower prices for consumers.

The energy minister, Josh Frydenberg, has added the new ACCC report to the agenda for discussion at the critical August meeting.

Nationals this week have attempted to front-run the debate and shape public perceptions of the report by claiming the ACCC investigation supports government backing of new coal generation, when the relevant recommendation is clearly technology-neutral.

The ACT’s climate change minister, Shane Rattenbury, told Guardian Australia the report was being used by Liberals and Nationals “shamelessly to back up each of their internal arguments about the Neg”.

He warned: “Unless the Coalition sorts out what the Neg will finally look like, it will be impossible for Coag to endorse or reject it.”

Frydenberg and the prime minister, Malcolm Turnbull, have both said the proposed government underwriting would apply to all technologies that met the criteria, including, potentially, coal projects, as well as gas and renewables with battery back-up.

But Turnbull has also pushed back against the Nationals. On Thursday Turnbull said: “We are not in the business of subsidising one technology or another. We’ve done enough of that. I mean, frankly, too much of that has been done.”

He said subsidies for various forms of energy were in the process of winding down “and we should simply allow the technologies to compete”.

Turnbull said the outcome the government was seeking was lower energy prices.

The shadow federal climate change minister, Mark Butler, has declared it is a “fantasy” that anyone would seek to build a new coal-fired power station underwritten by the commonwealth, and he warned government MPs against hijacking a useful investigation by Australia’s competition watchdog.

Butler said the idea of the government underwriting new market entrants with generation projects was an idea “very worthy of consideration, but unfortunately it’s already been hijacked by these ideological zealots in the Coalition party room”.

“Everyone in the industry has recognised that building new coal-fired power stations, one isn’t suitable for the nature of the market in the future; it’s not sufficiently flexible, it’s more expensive than other power options, but also there is very substantial carbon risk, regulatory risk, price risk, associated with building new, high polluting, or high emitting assets,” Butler said.

“That’s why the industry won’t go near it, investors, bankers, won’t go near it, because they understand quite how risky it is.”