"That's a go, but they are still negotiating the specifics of the contract," a source within the Nevada's governor's office told CNBC on Wednesday afternoon. The source noted that it could be a week before the deal is official.
Nevada Gov. Brian Sandoval will hold a news conference on Thursday in Carson City to make a "major economic development announcement,'' according to a media advisory from the state. Tesla spokesman Simon Sproule declined to give details but confirmed Tesla officials would be at the event.
In July, the automaker announced that it had partnered with Japanese electronics firm Panasonic to build the 35 GWh cell factory. It also said it would announce additional partnerships in the coming months.
Analysts at Lux Research expect the "gigafactory" to reduce the cost of the Tesla Model 3 by $2,800, which it says is "not enough to sway the success of the planned lower-cost EV."
Tesla also considered California, New Mexico, Arizona and Texas as possible locations for the factory.
—CNBC.com staff. CNBC's Mark Berniker and Reuters contributed to this report.