Teck Resources' biggest shareholder, China Investment Corp (CIC), currently favours Glencore's takeover plan that would allow investors to exit their coal exposure in return for cash, as the two miners race to win support for their competing proposals.

Glencore wants to buy Teck and then spin off the combined companies’ coal assets, but Teck says the deal is a “non starter” and is instead pressing ahead with an earlier plan to hive off its coal mines and focus on metals. Teck investors will decide on the Canadian miner’s split plan on April 26, in a high-stakes vote that is being framed by Glencore’s camp as a referendum on its takeover proposal.

China’s massive sovereign wealth fund owns 10% of Teck’s Class B shares, putting CIC in a powerful position as Teck needs to secure two-thirds approval from both classes of shares, voting separately. While Canada’s Keevil family controls the fate of the company through “supervoting” Class A shares — and has rejected a deal with Glencore — the structure of this month’s vote means that investors with just a small percentage of total voting rights could end up scuppering Teck’s plan.

CIC currently favors Glencore’s proposal for the coal assets because it would allow for a cleaner exit for investors, according to people familiar with the matter. Glencore this week amended its earlier all-share proposal to add a cash component, offering to buy out shareholders that don’t want to keep exposure to coal.

The fund is considering a vote against Teck’s own proposal, although it has yet to make a final decision, said the people, who asked not to be identified discussing private information.

CIC may still seek a higher price from Glencore before supporting its offer, some of the people said. Senior Glencore executives have spoken with CIC executives to try and win support for its proposal.

CIC and Glencore both declined to comment. The Chinese fund initially bought a 17% stake in Teck during the 2009 financial crisis, as the miner sought cash to cut its debt pile. CIC sold down some of its holding in 2017.

Tension between the two companies escalated publicly in recent days, with less than two weeks on the clock until Teck’s shareholder vote. Glencore has said its current proposal would be dead if Teck’s investors approve the separation, while a vote against would leave the company without a clear strategy — potentially putting pressure on the board and Keevil family to engage with Glencore.

Teck on Thursday rejected Glencore’s amended proposal, and also announced changes to its own planned split by reducing the minimum term of the royalty paid to the Teck metal company, to three years from more than five earlier. However, Teck investors would still be left holding a stake in the steelmaking coal business, versus the cash exit being offered by Glencore.

Both companies are trying to win investor support. Teck CEO Jonathan Price and Glencore CEO Gary Nagle both held investor meetings in Toronto Thursday, with Nagle meeting or speaking with more than 100 investors.

Glencore won a significant boost Thursday when influential proxy advisory firm Institutional Shareholder Services said Teck shareholders should vote against Teck’s proposal.