With time running out on its $43-billion pursuit of Anglo American, BHP Group faces a critical question: what would it take to draw the smaller company to the negotiating table within the next few days?

BHP’s plan to partially break up and then acquire Anglo has transfixed the mining industry by pitting two of its biggest names against each other in a public tussle. Anglo has already rejected two non-binding proposals from BHP — criticizing both the valuation and complexity — and instead rushed out a dramatic restructuring plan of its own.

Now, all eyes are on BHP: By 5pm London on Wednesday, the world’s biggest miner must either announce a firm intention to make an offer, or walk away for six months under UK takeover rules.

BHP is considering whether to make an improved proposal, but had yet to do so, according to people familiar with the matter. The world’s biggest miner would like some sign of engagement from Anglo to make a firm offer, some of the people said, and one way to achieve that could be with a proposal attractive enough to convince Anglo’s own investors to push the company to enter talks.

Still, BHP is wary of bidding against itself in a vacuum, and walking away remains a strong possibility. The company currently has no intention of going hostile with an offer to Anglo’s shareholders if the board refuses to engage with it.

Spokespeople for BHP and Anglo declined to comment.

BHP CEO Mike Henry is trying to get his hands on Anglo’s copper assets, which are the envy of the industry, but wants Anglo to first spin off its South African platinum and iron ore businesses before proceeding with a takeover. The acquisition would be the industry’s biggest deal in over a decade and would create the world’s biggest copper producer — accounting for roughly 10% of global supply — at a time when mining companies and their investors are positioning to benefit from a looming supply deficit.

The approaching deadline follows a drama-filled week, in which BHP revealed that it been rebuffed for a second time after increasing the number of shares it was offering for the rest of Anglo. A day later, Anglo CEO Duncan Wanblad unveiled his own plan to reshape its business by exiting platinum, diamonds and coal and slowing an unpopular fertilizer project.

BHP has been emboldened by Anglo’s announcement given the similarities to its own plan — particularly the proposal to spin off the platinum business — and the company is now weighing how it might draw Anglo shareholders into the fray to pressure the smaller miner to begin discussions.

Technically, Anglo could ask for an extension to the deadline, but as things stand it has no intention to do so, people familiar with the matter said.

And while some shareholders have warmed to Anglo’s plan this week, its two biggest holders, BlackRock Inc. and South Africa’s Public Investment Corp., have yet to express a public view on which approach they would favour. The pair will be pivotal, holding about 18% of Anglo’s stock between them.

Meanwhile, activist Elliott Investment Management has also built a stake in Anglo and is currently assessing its options, another person said.

Speaking privately, several of Anglo’s other large shareholders said that they had not been convinced by BHP’s latest proposal. They also indicated a lack of urgency, saying that Anglo’s plan to slim itself down and focus on copper increased the likelihood that BHP or one of its rivals would target the company for a takeover in the future, if the current attempt doesn’t succeed.

However, BHP’s own shareholders may be sceptical if a restructured Anglo demands a better valuation.

“The problem is, if they take out that risk, they come back in a year’s time, they have to pay a higher 30% premium on Anglo share prices in a years’ time when it’s in a better situation,” said Hugh Dive, chief investment officer of Atlas Funds Management in Sydney, which owns BHP shares.

BHP’s current offer values Anglo — including the majority stakes it holds in the listed South African companies — at £29.45 a share. Anglo closed on Friday at £26.775 in London, suggesting investors are pricing in a lower likelihood of a deal, but remains about 27% higher than the day before the BHP approach was first reported by Bloomberg.

In conversations with five of Anglo’s top-20 shareholders, most said they thought that Anglo’s plan has put the company on a surer footing, at least for the immediate goal of fending off BHP’s current takeover attempt. Several said that they particularly welcomed the belt-tightening promised at the UK fertilizer project.

If Anglo’s management can achieve its ambitious portfolio overhaul, the shareholders agreed that the leaner copper and iron ore business will be a much more attractive target than the sprawling company is today – something they said won’t be lost on Rio Tinto Group and Glencore. For now, however, most of the investors said that neither of the visions for Anglo outlined so far by Henry or Wanblad is clearly superior, and they could be persuaded by both sides.

BHP currently has no intention of taking its offer directly to Anglo’s investors in a hostile bid, several of the people said. Such a move would not allow for BHP to conduct due diligence on Anglo’s assets and would risk invoking the ire of its own shareholders, who have demanded the company stays disciplined. It would also require it to bid for all of Anglo — including the parts it’s insisting Anglo hive off as a prerequisite for a deal.

That means BHP needs Anglo to engage and agree to talks. But the clock is running down.