LORDSTOWN — The United Auto Workers union said it plans to persist with an effort to organize employees of Ultium Cells LLC after claims the company turned away a proposed card-check agreement for workers at the battery-cell maker’s factory in Lordstown.

According to a letter Tuesday to local union leaders from UAW Vice President Terry Dittes, the UAW-GM Department met with Ultium Cells leaders and presented a basic card-check agreement, but Ultium Cells “flat-out rejected” the proposal.

The proposal would have given the UAW access to the facility to collect cards — a move to determine interest among employees to unionize under the UAW.

“If the majority is established by an independent third party, the union would be recognized and negotiations would commence,” Dittes wrote. “This process has been agreed to by many employers for a smooth and peaceful recognition of the UAW. Ultium has flat-out rejected those simple basic features of a card-check recognition we proposed.”

Ultium Cells is a joint venture between General Motors and South Korea’s LG Energy Solution to mass produce electric-vehicle battery cells at plants in Lordstown and elsewhere across the U.S. The company plans other plants in Lansing, Mich., and in Spring Hill, Tenn., plus a fourth plant, the location of which has yet to be announced.

In Lordstown, production is scheduled to begin in August. At full capacity, the $2.3 billion factory that’s nearing completion will employ about 1,100 workers. It will be the first of the plants to start producing battery cells.

“We have just kicked off our organizing drive at Ultium in Lordstown, Ohio,” Dittes wrote. “We will represent the employees there and at all the future Ultium sites currently under construction. We will not be slowed down to organize workers who want to join our union!”

In a emailed statement Wednesday, Dittes said, “Our union remains committed to organizing Ultium along with every electric-vehicle (EV) component supplier and electric-vehicle (EV) joint venture. We continue to encourage all employers to recognize the majority will of their workers rather than to follow the counsel of anti-union consultants who want to put workers through the gauntlet of an anti-union campaign.”

Brooke Waid, spokeswoman for Ultium Cells, said the company has had initial talks around a neutrality agreement that could enable card check at the Lordstown factory.

Under a neutrality agreement, the employer agrees to remain neutral in any employee organizing effort by a union.

“We are, and always have been, supportive of the process that allows our people to determine their own representation status, which is a matter of personal choice,” Waid wrote in email that also stated the company “is not aware of any current organizing efforts” at the local factory.