The Turnbull government believes its decision not to run a Liberal candidate in the Batman byelection will pay big dividends next weekend, but Bill Shorten is no willing sitting duck.

The plan is, without its second preferences, Labor will succumb to a Greens Party onslaught. An added bonus is the exposure of the Labor leader as a duplicitous opportunist over his attitude to the controversial Adani coal project.

But on Tuesday Mr Shorten flicked the switch to economic management and tax reform, willingly opening himself up to more charges of “class warfare”.

That’s the plaintive cry from the government and its business cheerleaders whenever Mr Shorten and his shadow treasurer Chris Bowen unveil yet another policy to close tax loopholes worth billions to the budget bottom line.

In Labor’s sights this time, about 200,000 self-managed super funds making a motza out of a Howard-era tax concession that allows them to cash out dividend imputation credits. This is a handout on top of having personal tax on their share earnings waived. By blowing the whistle on it the budget will be saved $6 billion a year.

Labor claims 92 per cent of taxpayers won’t be touched but it will be in a much better position than the government to give them a real income tax cut.

The announcement comes on top of other budget repair measures already announced, like negative gearing and capital gains tax reform, closing discretionary trusts loopholes and putting a cap on the deductibility of managing tax affairs.

Sure, it can be painted as socking the rich (or rather the very rich). But unlike the government’s $65 billion worth of corporate tax cuts to the biggest companies, many of them multinationals, it won’t be paid for by cuts to health, education and family payments.

The government’s option is to match it – or decry it as ending the world as we know it. But Mr Shorten has no less an expert than former Liberal leader and economics professor John Hewson on side.

Dr Hewson agrees that in economic terms these cash refunds “don’t make any sense at all”.

Labor is confident it is on the right side of this argument as far as most voters are concerned. Just as Mr Shorten believes the hardening up of his criticism of the Adani coal mine is similarly endorsed.

It is true that ahead of the 2016 election Mr Shorten said the Adani project “had to stack up environmentally and financially” but he hoped it would. Now he’s lost faith in it, citing the project’s failure to find funding from 27 banks and having missed seven deadlines. As well, he has new environmental concerns.

Malcolm Turnbull is not alone in accusing the Labor leader of being slippery. Focus groups conducted by the University of Canberra in South Australia found the same thing.

But surely the rub is this: Mr Shorten’s new stand is endorsed by an overwhelming majority of Australians; 67 per cent according to a ReachTEL poll in January.

The same poll for The Australia Institute has now found a huge 74.4 per cent of constituents in the Prime Minister’s own seat of Wentworth supported a review of the environmental approval for the Adani mine.

In the broader scheme of things it is Mr Turnbull who also needs to switch his thinking because the issue will fester long after this weekend’s result is known.

It feeds into the broader public sentiment of concerns over climate change and energy policy. Indeed, there is a view in Adelaide that Mr Turnbull’s attack on renewable energy after the South Australian blackouts has fed very badly into that state election to be held on the same day as the Victorian byelection.

Both elections are looking tight affairs. Whatever the outcomes, the federal budget will still be in need of repair and the nation in urgent need of a credible energy policy.

Paul Bongiorno AM is a veteran of the Canberra Press Gallery, with 40 years’ experience covering Australian politics.