The Turnbull government will go to the election promising Australians it will make no changes to negative gearing and capital gains tax, the prime minister and treasurer have said.

In a further indication of the Coalition’s election policies Michaelia Cash, the employment minister, told Sky News the government would back a policy of “incremental” industrial relations changes.

In a joint statement Malcolm Turnbull and Scott Morrison said there would not be changes to negative gearing or capital gains tax policy in the budget on 3 May.

“Labor’s housing tax plan will deliver a reckless trifecta of lower home values, higher rents and less investment,” they said.

“Driving down the value of the most important asset for most Australians is not a strategy for economic growth and enhanced prosperity.”

Turnbull and Morrison nominated increasing the supply of land and changing zoning for residential construction as the solution to housing affordability.

The comments ruled out reports the government was considering capping negative gearing from rental losses at $20,000.

Cash said homeowners would be harmed “if you take $1 off [the value of] their house, the asset they have worked hard for, that’s going to see them to retirement”.

Cash criticised Labor’s policy to limit negative gearing to new housing stock, saying it would push up prices for new homes. Morrison said people who bought new homes would lose out when they sold them into a different market in which fewer investors participated because they could not negatively gear existing properties.

On channel nine’s Sunday program shadow treasurer, Chris Bowen, said the decision not to change negative gearing rules meant Malcolm Turnbull didn’t care about housing affordability.

He said Labor’s policy was carefully calibrated to protect existing investments, use negative gearing to encourage new housing supply and to bring first home buyers into the market.

Asked whether the policy would hit house prices, Bowen said it would “put first home-buyers on a more level playing field” but dismissed claims prices would crash as a lie.

Appearing on the ABC’s Insiders program on Sunday, the manager of opposition business, Tony Burke, said the government was running a fear campaign that contradicted itself, as ministers had claimed both that house prices would go up and down.

“They have no economists who have been out there backing in this fear campaign they’ve wanted to run,” he said.

Burke said Malcolm Turnbull was “arguing that the second, third and 10th home-buyer should get more government assistance than the first homebuyer”.

Cash said the government was finalising its response to the Productivity Commission review of workplace laws after consulting stakeholders.

She said the Coalition’s industrial relations policy would be laid out ahead of the election but would focus on incremental rather than radical change.

“Are we going to swing the [industrial relations] pendulum to the right? No we’re not. Stakeholders, what they want to see is industrial relations policy that will bring the Australian people with us and get through the Senate.”

Cash said the Senate was prepared to accept incremental change but “the last thing I want to do is put up policy that is destined to fail”.

Cash said her two goals in industrial relations policy were maintaining a strong safety net, which she said she was “fundamentally committed to”, and removing disincentives to employment.

“We have a problem with youth unemployment in this country. We want underemployed people to be able to do additional hours, and for business to be able to prosper and grow without compromising the safety net.”

Cash said that, if elected, Labor would restore the Road Safety Remuneration Tribunal, which sets minimum pay rates for truck owner-drivers to improve safety outcomes.

The government was able to abolish the tribunal with crossbench support over fears higher rates for independent contractors would prevent them being able to compete with employee drivers and they would lose work.

Cash also said the Liberal party needed to do more to preselect women, after a string of preselections in lower house seats chose male candidates, including to replace outgoing MPs Sharman Stone and Bronwyn Bishop.

She welcomed the party’s decision to adopt a target of 50% of seats to be contested by women by 2025, which she said was a “generous” goal.

But Cash declined to criticise results of recent preselections: “It won’t surprise anyone that I’ve always said the best candidate on the day should be preselected. If that’s a woman, fantastic; if that’s a man, fantastic.”

“If there is a preselection and no woman stands, that’s deplorable,” she said.