Tony Abbott has fired off a fresh broadside, declaring the Turnbull government has undermined its own “good story” on citizenship because “some genius” sought to leak internal polling from his electorate of Warringah from the last federal election.

The former prime minister told reporters outside his electoral office in Sydney on Thursday he was “incredibly disappointed” by the leak, which he contended had occurred to “advance someone’s interest”.

“The government actually has a very good story to tell today,” Abbott said. “We are toughening up the citizenship test. That’s good. We are making it easier for Australian jobs to go to Australians. That’s good.

“Why on earth some genius would seek to derail the government’s message in this way is just absolutely beyond me.”

The leak of the polling came on the same day the government unveiled proposed changes to the citizenship test that have been in gestation inside the government for some months.

Abbott has declared only two people apart from himself were aware of the Warringah polling, which demonstrated he was under pressure from independents during last year’s election – the prime minister, Malcolm Turnbull, and the Liberal party’s former campaign director Tony Nutt.

Turnbull, who travelled to Tasmania after launching the government’s proposed changes to the citizenship laws, told reporters there he didn’t know who was responsible for the leak, which he characterised as “regrettable”.

But he said the government was intent on getting on with business. “We are getting on with the job,” Turnbull said.

The wrangle between the former and current prime minister followed Turnbull confirming the government’s intention to raise the bar for Australian citizenship by requiring migrants to pass a tougher English language test and to live in Australia for four years as a permanent resident.

The overhaul of the citizenship process follows the Coalition’s move earlier in the week to overhaul skilled migration by replacing 457 visas with two new categories.

The prime minister moved quickly on Thursday to pile political pressure on Labor to support the proposed citizenship reforms, declaring they were not about administration, they were “about allegiance and commitment to Australian values”.

Speaking to reporters in Port Kembla, the Labor leader, Bill Shorten, indicated the opposition would likely support the process changes, such as making the English language test more challenging and requiring a four-year waiting period.

“I think it is reasonable to look for English language proficiency and I think that it’s reasonable to have some period of time, waiting time, before you become an Australian citizen,” the Labor leader said.

But he said the package was about a prime minister in political difficulty rather than a response to any substantive policy problem.

“Let’s call it as it is,” Shorten said. “Does anyone think that if Tony Abbott wasn’t causing the division and the internal fighting with Malcolm Turnbull that we’d be talking about this today?

“For me, it’s not about a citizenship issue. It’s about Malcolm Turnbull desperate to save his own job from Tony Abbott.”

Shorten objected to the prime minister linking Labor’s support for the citizenship package to whether the opposition was supportive of efforts to curb domestic violence.

The prime minister signalled would-be citizens would be required to affirm “Australian values” such as rejecting violence against women and child marriage, and argued everyone should be supportive of beefing up the values component of the citizenship process.

“I’ll tell Malcolm Turnbull where Labor stands,” Shorten said. “We stand for making sure there are not cuts to the legal centres who protect the victims of domestic violence.

“We stand for making sure that the victims of domestic violence are not cross-examined by their assailants in court.

“We’ve written to Malcolm Turnbull, time and time again, to do more for domestic violence and he simply hasn’t bothered responding.”