The federal opposition has described the deal as a net zero "failure", while the Greens want the government to own a stake in the smelter.

Prime Minister Anthony Albanese and NSW Premier Chris Minns are expected to travel to Tomago just outside Newcastle to announce the deal on Thursday.

Anthony Albanese and NSW Premier Chris Minns are poised to sign a bailout agreement for the beleaguered Tomago aluminium smelter, ending months of uncertainty for workers.