Bill Shorten has vowed to keep the energy supplement in place if Labor is elected to government.
Draft laws to scrap the energy supplement for anyone who has become a new pension or allowance recipient since September 20, 2016, are currently before the federal parliament.
Axing the energy supplement will mean a cut of $14.10 per fortnight to single pensioners or around $365 a year, and a cut of $21.20 a fortnight or around $550 a year to couple pensioners.
"If Turnbull gets this legislation through, in the 2020-21 financial year alone more than 592,000 age pensioners will have less in their pockets every fortnight," Mr Shorten said.
Over the decade it would adversely impact on 1.5 million pensioners, according to Labor's figures.
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The payment was initially made as compensation for the carbon tax.
Mr Shorten said that at a time when energy prices were on the rise the last thing pensioners needed was a cut to their household budget.
"Taking the axe to the pension and making pensioners worse off is another example of Turnbull's out-of-touch priorities," Mr Shorten said.
The opposition leader will take his message to the Queensland seat of Longman on Sunday, a week out from a Super Saturday of five by-elections.
Longman is looking like Labor's toughest test, with Susan Lamb up against the Liberal National Party's Trevor Ruthenberg.
