Shareholders in Refining New Zealand will decide today whether a $365 million upgrade will go ahead at the company's Marsden Pt facility and insiders say the voting will be close.
The size of the project means the company needs a simple majority at today's annual meeting to approve expenditure for the construction project.
In February, a majority of directors resolved to support investing in a Continuous Catalyst Regeneration Platformer, which would enable the company to expand its petrol refining capacity to meet 65 per cent of local needs from the current 55 per cent.
But the board's vote was not unanimous.
Refining NZ conducted a national roadshow last week to garner shareholder support for the upgrade, which comes at a time when many refineries around the developed world are struggling.
Declining margins have put downward pressure on the company's share price, which closed yesterday at $2.75, down from $4.56 last May.