SYDNEY, Nov 17 (Reuters) - Origin Energy shareholder VanEck Australia will support the $10.5 billion bid from Canada's Brookfield and EIG, according to a senior executive, one of only a handful of funds to reveal their hand ahead of the shareholder vote next Thursday.

The Brookfield consortium's A$9.53 offer is a "good premium" given the uncertainty around Origin Energy's ability to profit from the shift to renewable energy, according to Jamie Hannah, deputy head of investments and capital markets at VanEck, which owns a 0.3% stake in Origin.

Critics of the bid argue it undervalues Origin's 20% stake in British renewable energy utility Octopus Energy, but Hannah said the assets are tricky to price.

"Lots of other shareholders are putting a big premium there but its hard to quantify where it will go," he said, echoing an argument made by proxy adviser CGI Glass Lewis when it backed the deal last week.

"The current premium is a good premium and if the deal doesn’t go ahead it will struggle to maintain its price."

Origin Energy shares traded up 0.5% at A$8.78 around midday local time.

Despite backing the deal, Hannah said it was unlikely to pass at the meeting against opposition from AustralianSuper, the country's largest pension fund.

The A$300 billion fund has waged a public campaign against a deal it says sells Origin cheap. Its 16.5% stake is short the quarter votes needed to block the bid outright but is likely to carry extra weight given retail shareholders often do not vote.

The tight race means even a single small institutional shareholder backing AustralianSuper could sink the deal.

While none have publicly backed AustralianSuper, Vince Pezzullo, head of equities at fund manager Perpetual on Wednesday criticized how Brookfield and EIG had conducted their campaign in comments reported by The Australian newspaper.

Perpetual, reported to hold around 3% of Origin shares, has not divulged how it will vote. A spokesperson declined to comment. (Reporting by Lewis Jackson; Editing by Michael Perry)