Thousands of Costco workers prepared to strike with a midnight deadline drawing closer Friday while the worker's union and the company negotiated.

The Teamsters union represents 18,000 Costco workers in six states: California, Washington, Maryland, Virginia, New Jersey and New York.

It's unclear if the strikes would close stores. Costco has 219,000 U.S. employees and 617 U.S. stores. The company said its labor agreement with the Teamsters applies to less than 10% of those stores.

On Jan. 20, Teamsters members at Costco voted overwhelmingly in favor of a strike if a new three-year contract agreement wasn't reached by midnight Friday, when the current contract expires.

Union members say the Issaquah, Washington, company needs to make a contract offer that reflects its sales and profit growth. Costco's revenue rose 5% to $254 billion in its most recent fiscal year, which ended Sept. 1. The company reported net income of $7.36 billion, double its profit in 2019.

"Costco has two choices: respect the workers who made them a success or face a national strike,” Teamsters General President Sean O’Brien said in a statement. “Costco Teamsters deserve an industry-leading contract that reflects the company’s massive profits. If Costco thinks they can exploit our members while raking in billions, we’ll shut them down.”

Costco said in a statement that it has had a good relationship with the union for several decades and is negotiating in good faith.

“We have always treated our employees fairly and well throughout the history of our company,” Costco said.