Pension giant AustralianSuper has again rebuffed Brookfield Asset Management and EIG Global Energy Partners’ A$19.4 billion ($12.6 billion) takeover plan for Australian utility Origin Energy Ltd.

The country’s largest pension fund, which is Origin’s biggest investor with 15.3% of shares, said in a statement Monday it had “rejected an eleventh hour and unsolicited letter” from the private equity firms and “reaffirmed that it will be voting against” the company’s takeover.

“The letter contained an offer for AustralianSuper to engage with the consortium in relation to acquiring interests in Origin,” should the deal be successful, the A$300 billion pension said.

A Brookfield spokesman confirmed the contents of the letter but declined to comment further.

A shareholder vote to decide the deal’s fate is scheduled for Nov. 23. AustralianSuper had already maintained it had no interest in participating in the take-private as a co-investor, even after the Brookfield-led consortium had rushed to open a dialog.

“AustralianSuper is a long-term investor in the Australian economy and is open to providing capital to assist Origin as it prepares to transition over the coming decades,” it said in the statement.

Australian rules require a minimum of 75% of participating shareholders to approve a takeover offer, meaning 15% opposition has usually proved sufficient to block a deal as typically not all retail investors will cast a ballot.