By Scott Murdoch and Lewis Jackson

SYDNEY A Brookfield-led consortium's A$16.3 billion ($10.61 billion) bid for Origin Energy is expected to fail after the largest shareholder in Australia's biggest energy retailer said it would vote against the offer at an investor meeting on Thursday.

Australian Super, which has a 16.5% stake in Origin, said it believes the offer substantially undervalues the company's ability to profit from the shift to renewable energy, and has already said it would vote no.

Without the support of the A$300 billion pension fund, Australia's largest, the consortium will struggle to receive the level of backing it needs to succeed under local takeover laws.

Proxy votes were due to be lodged on Tuesday, meaning major institutional investors have already voted, but a shareholder meeting will be held in Sydney on Thursday at 0300 GMT. The deal would be Australia's second largest buyout in 2023 after Newmont Corp paid $17.8 billion for Newcrest Mining.

The energy company's shares closed on Wednesday at A$8.42, up 1.69%, but well below the offer price of A$9.43 per share.

Brookfield Corp, which has teamed up with EIG Partner's MidOcean Energy, has offered Origin shareholders A$6.59 and $1.86 in cash and a A39c special dividend.

At the time of the new offer on Nov 2, the bid equated to A$9.53 per share, but foreign exchange volatility has pushed that down to the current level.

The subdued share price suggested investors did not believe the deal would go through, according to Jamie Hannah, deputy head of investments and capital markets at VanEck Australia, which voted its 0.3% stake in support of the deal.

"I'm not confident of it going ahead. As much as we've voted for it, I don't know if the numbers stack up. If everyone thought it was going ahead the share price would be higher," he told Reuters.

Brookfield and Origin Energy declined to comment on Thursday's vote.

Origin shares remain 2.1% lower than last week's close and have traded well below the offer price since the new bid arrived, suggesting investors were pessimistic of its success.

"With Australian Super interest increasing 16.5% in Origin, the probability is that the EIG/Brookfield scheme will fail," Macquarie analyst Ian Myles wrote in a recent note.

($1 = 1.5366 Australian dollars)

(Reporting by Scott Murdoch and Lewis Jackson; editing by Miral Fahmy)