Labor leader Bill Shorten has promised to invest $75 million to discovering mining resources if he wins the election.

Mr Shorten says the money will reverse the Liberals’ decision to stop the Exploring for the Future program, which uses technology to find future deposits by developing underground maps to show where minerals are.

About two-thirds of Australia’s potential mineral deposits remain undiscovered.

“We want to ensure Australian mines are powering the commodities of the future – such as lithium – as we build the renewable energy economy,” he said.

Labor wants lithium batteries to be made domestically, seeing potential in the industry that will store renewable energy and power electric cars and smartphones.

The opposition leader is in Perth on Monday, where he will also pledge to make the South West region of WA a “renewable energy zone”.

The region will benefit from support from Labor’s $5 billion energy securitisation and modernisation fund, allowing for increased investment in renewables.

At present, 7.5 per cent of the area’s power comes from renewables and Labor wants to significantly boost this proportion.

Mr Shorten will debate Prime Minister Scott Morrison on Monday night, the first of three leaders’ debates locked in ahead of the May 18 election.

Mr Morrison’s coalition has narrowed the polling gap with Labor to 51 per cent to 49 on the two-party preferred vote.

But the coalition’s primary vote has dropped one point to 38 per cent, while Labor’s is down to 37 per cent.

The poll comes after the first two weeks of the campaign where Mr Morrison focused heavily on the economy and attacking Labor’s tax plans.

Mr Shorten has justified his changes to the tax system by saying the money would go towards services such as education and health care.

But he is yet to say how much the changes will rake in.

The Labor leader was back home in Melbourne on Sunday, where he made three major policy announcements at a rally of party faithful.

Mr Shorten promised $1000 of free dental work for aged pensioners, more subsidies for child care and a 20 per cent pay increase for early educators.

Labor will try to hold its five of 16 WA seats, though the coalition is eyeing Cowan which opposition MP Anne Aly holds by a margin of 0.07 per cent.

Attorney-General Christian Porter’s seat of Pearce, which he holds by 3.6 per cent, is expected to be in fierce contention at the election.

Monday’s debate will be held at 5pm local time and will feature questions from The West Australian readers.