A Roy Morgan poll – conducted in the past week after an onslaught of criticism of Morrison from people within his own party – shows the ALP extending its lead to 57-43 in two-party preferred terms.

But the prime minister brushed off polls showing the opposition could win the next election, telling the ABC’s 7.30 program on Tuesday, “elections are always tight”.

“It’s a tough job, and it’s been a tough time, and people have had a tough time of it over the last three and a half years,” he said.

“As prime minister, you’ve got to take all the slings and arrows – and I do – but I never lose my focus on the job.

“I’ll always stand up to the things that are trying to take our government off in the wrong direction.”

On Tuesday, the NSW Court of Appeal dismissed a legal challenge to the selection of Liberal candidates in three NSW seats after Morrison intervened in the process.

The court upheld the federal intervention, enabling the re-endorsement of his ministers Alex Hawke and Sussan Ley, along with backbencher Trent Zimmerman.

Morrison told 7.30 he intervened originally to protect female candidates whose positions were being threatened by factions within the NSW branch.

“I’m asked all the time, ‘Why won’t the Prime Minister do more about getting good women in parliament and stand up for the women in parliament?’ So I stood up for the women in my team.”

Liberal senator Concetta Fierravanti-Wells, who has been relegated to an unwinnable spot on the party’s NSW Senate line-up, rejected his response that he was protecting women.

In a statement to 7.30 she said: “Morrison is simply using the ‘gender card’ to conflate captain’s picks to trash democratic processes in NSW. I do not accept criticism from a person who lacks a moral compass.”

Senator Fierravanti-Wells last week spoke under parliamentary privilege to condemn Morrison as “not fit to be prime minister” and branding him “ruthless”.

Meanwhile, the opposition is trying to focus voters on their vision for the country if successful in May.

Australia’s newborn screening program will be updated for the first time in four decades under a Labor government.

Labor has promised to invest more than $38 million to introduce a universal screening program for Australian states and territories.

Currently, the screening test differs depending on the state and most hospitals only test for 25 conditions.

The funding will increase the number of conditions screened to 80, which is best practice worldwide.

Opposition Leader Anthony Albanese said if elected a federal Labor government would work with the states and territories to deliver a better national newborn screening program.

This would include a regular process to update the screened conditions based on expert advice, he said.

Shadow treasurer Jim Chalmers on Tuesday reiterated Labor has no plan to raise taxes other than ensuring multinationals pay their fair share of tax to pay for election commitments.

He also promised not to overturn already-legislated income tax cuts due to roll out in 2024.

Australians are set to go to the polls on May 14 or May 21.