"I would put the odds at no better or worse than 50/50," Mr. Bhar said.
A stronger dollar was also weighing on the metal on Wednesday, after Federal Reserve Chairwoman Janet Yellen raised expectations for a rate increase next month. The WSJ Dollar Index was up 0.18% on Wednesday. A stronger dollar makes dollar-denominated commodities more expensive for buyers who hold other currencies.
The union talks come amid a supply pinch, after Freeport-McMoRan Inc. said it had stopped production at its Grasberg mine in Indonesia because it had not yet received an export license for the mine, following new regulations for exports introduced by the government in mid-January.
Nickel rose to a 10-week high on Wednesday after the Philippines Department of Environment and Natural Resources said Tuesday that it planned to cancel 75 contracts with mining companies because of environmental concerns. However, those projects aren't yet producing nickel, so the cancellations are more likely to affect long-term production and prevent new mining projects.
Nickel prices were up 0.42% at $10,835 per metric ton on Wednesday.
The other base metals were mixed. Aluminum was up 0.32% at $1,892 per ton, lead was down 0.27% at $2,358.50 per ton, zinc was down 0.50% at $2,885 per ton and tin was up 0.88% at $19,965 per ton.