Tony Abbott has denied breaking an election promise over education funding and the Gonski reforms, insisting he never vowed to maintain the same money for each school.

His argument that the promise was "plural" – matching total funding for all schools – comes despite the education minister, Christopher Pyne, declaring before the election: "You can vote Liberal or Labor and you'll get exactly the same amount of funding for your school."

Abbott also told voters on 2 August that he would end uncertainty by "guaranteeing that no school will be worse off over the forward estimates period" – a reference to the four-year budget cycle.

In an interview with the conservative commentator Andrew Bolt on Sunday, Abbott focused on his broader commitment to match Labor's total funding for schools over four years. The prime minister said he was happy to say schools would get the same total amount of funding over the next four years, plus extra for schools in Queensland, Western Australia and the Northern Territory where governments did not sign up to Labor's Gonski reforms before the election.

But Abbott insisted his promise to match funding did not apply to each individual school, in an apparent concession that the government's decision to rewrite the funding model after 2014 could lead to winners and losers.

"Well I think Christopher [Pyne] said schools would get the same amount of money, and schools – plural – will get the same amount of money. The quantum will be the same; in fact we're going to put a little bit more in," Abbott said on Ten's Bolt Report.

Bolt told Abbott that voters heard a promise about matching funding for each school – "singular".

"But, Andrew, we are going to keep our promise," Abbott replied.

"We are going to keep the promise that we made, not the promise that some people thought that we made, or the promise that some people might have liked us to make."

The opposition leader, Bill Shorten, said Abbott's pre-election pledge now appeared to be a lie to shut down a damaging political debate over school funding. "Mr Abbott has broken that promise, pure and simple. No amount of weasel words can get Mr Abbott out of this clear breach of trust," Shorten said.

On 2 August, nearly a month before the election, Abbott fronted the media to say Labor had been using school funding as a political wedge and schools needed certainty. "As far as I'm concerned, as far as Christopher Pyne is concerned, as far as the Coalition is concerned, we want to end the uncertainty by guaranteeing that no school will be worse off over the forward estimates period; we we will honour the agreements that Labor has entered into; we will match the offers that Labor has made; we will make sure that no school is worse off," Abbott said.

During that media conference Abbott flagged changes to the level of federal regulation of state education issues, saying the difference between Labor and the Coalition was "not over funding" but over the level of control Canberra should have. "What I want to say today is as far as school funding is concerned, Kevin Rudd and I are on a unity ticket," Abbott said.

On 21 August Pyne issued a statement that said: "Every single school in Australia will receive, dollar for dollar, the same federal funding over the next four years whether there is a Liberal or Labor government after September 7." That media release remained on Pyne's official website on Sunday.

After Abbott's statements to Andrew Bolt on Sunday, Labor immediately accused him of playing word games. The opposition education spokeswoman, Kate Ellis, said the Coalition's backflip was a betrayal of students, teachers and parents.

"A promise is a promise and no clever words from Mr Abbott now can disguise the fact they have clearly broken that promise," she told Ten's Meet the Press programme.

Ellis said the government was underestimating the strength of community feeling on the school funding issue.

The South Australian Labor premier, Jay Weatherill, who faces a tough state election next year, vowed to "extract a political penalty" for every day the government was in breach of its promises.

"They know that they can't be seen to break a promise so that's why they're pretending they didn't break a promise," Weatherill said.

Pyne announced on Tuesday that he would keep Labor's Gonski-based school funding model for only the first year of implementation, 2014, and then impose with a yet-to-be devised system based on what the federal government argues is fair to all states.

He announced on Wednesday $230m for the three conservative jurisdictions that did not sign up to the reforms before the election.

In a show of unity the education ministers from jurisdictions that signed a deal – the conservative-led New South Wales and Victoria and Labor-run South Australia, Tasmania and ACT – jointly fronted the media after a meeting with Pyne in Sydney to demand the government meet its election pledge to honour signed agreements on school funding.

The New South Wales education minister, Adrian Piccoli, led the attack on his federal Coalition colleagues, saying pointedly that the Abbott government had broken its election promises and the "parents of the millions of children" had a right to be disappointed.

He said he believed public schools could bear the brunt of the shake-up but Pyne said no one should make assumptions about the outcome. The Association of Independent Schools of New South Wales responded to the spat by declaring it did not want a greater share of federal funding at the expense of public schools, fearing a return to private-public schooling "wars" of the past.

The Queensland premier, Campbell Newman, said on Sunday that he was delighted with the federal government's decision to provide funding for the state next year and accused other premiers of being prepared to "sell sovereignty of states down the river" by embracing Labor's model.

The Australian Education Union's deputy federal president, Correna Haythorpe, said parents, teachers and principals knew what they had been promised and the government must honour its commitment to match the funding dollar-for-dollar for at least four years.