Federal Opposition Leader Bill Shorten has made an election year pitch to voters, as senior Government members leave open the prospect of an early poll.

The ABC has been told Malcolm Turnbull is seriously considering calling a double dissolution election and going to the polls on Saturday July 2.

The trigger would be the Senate's expected rejection of a bill to reinstate the construction watchdog, the Australian Building and Construction Commission (ABCC).

"[A double dissolution] is obviously available in circumstances where bills have been rejected within the appropriate time period," Mr Turnbull said on Friday.

Mr Shorten said his party was ready to fight an early election, saying its campaign would revolve around five issues.

"A fair taxation system, standing up for Australian jobs, [and] a properly funded Medicare system — where it's your Medicare card, not your credit card, that determines the level of your health care," he said.

"We'll fight it around schools, TAFE and universities, where working class and middle-class kids, every child, gets every opportunity in every school and we'll fight it on making sure we've got fair dinkum policies on renewable energy.

"[The Government] needs to stop threatening the Australian people with the threat of early elections, just to cover up their lack of action on the economy of Australia."

In another sign the political contest is intensifying, Mr Turnbull called an impromptu Friday afternoon press conference to ramp up his attack on the Opposition's plan to restrict negative gearing to new investment properties.

Mr Turnbull warned Labor's policy would "smash" house prices.

"Every home owner in Australia has a lot to fear from Bill Shorten ... his policies will make your home worth less," Mr Turnbull said.

"You have to look at it very carefully you have to apply great care and attention, you need to you need to use a scalpel if you like, not an axe — and what Bill Shorten has done, he has set out to smash the residential housing market."

Mr Turnbull's language has intensified significantly since earlier in the week, when he simply said Labor's plan was "not a well designed policy".

The Coalition has indicated it wants to tackle what it calls "excesses" in negative gearing, but Mr Turnbull's new aggression may indicate the Government is backing away from any substantial changes.

Labor was quick to accuse the Coalition of trying to regain some ground after enduring a torrid week and countless questions about why it is taking so long to reveal its planned tax changes.

Mr Shorten said Mr Turnbull's criticisms sounded like they were scripted by his predecessor, Tony Abbott.

"This is desperate stuff from a Prime Minister who has broken his promise to provide 'new economic leadership'. His Treasurer is off with the pixies and the Prime Minister is flailing desperately behind," he said.

Double dissolution a 'live option': Pyne

The Senate in mid-March is expected to again reject the ABCC bill before a seven-week break. Parliament would then next sit on federal Budget day, May 10.

For a double dissolution to happen, the Prime Minister would have to call the election the next day.

"Well that's an option, it's a live option — of course it is," Cabinet Minister Christopher Pyne said of a double dissolution.

However, he said the Government was a "long way from having an election in July", adding the Government wanted to see its legislation passed by the Senate.

"The election is due in about August or September, so if there was an election in July, I don't think the public would regard that as an early election," he said.

Senior Coalition sources said Mr Turnbull was listening to arguments for and against the idea.

A main argument being made for an early election is Mr Turnbull's popularity.

But some are wary of running a seven-and-a-half week election campaign, where the Government could lose control of the debate and voters could become fatigued. The cost of longer campaigning is also a factor.

The ABC has been told while no decision has been made, an election in September or October is still more likely than a double dissolution.

Mr Turnbull said he hoped the Senate would pass the ABCC legislation, but a double dissolution was an option if it was voted down.

"It is an option available to government in those circumstances, but at the moment your question is a hypothetical one," he said.

"It absolutely is a very important part of micro economic reform.

"It's a sector that employs over a million people, it's a very big part of the economy."