Delivery drivers from Teamsters Local 120 voted unanimously to strike O’Reilly Auto Parts in Minnesota unless the company agrees to a renewed labor contract that adds more drivers, eliminates complicated pay formulas and increases safety standards.

Union officials announced the move Friday in a statement that company officials said caught them off guard.

“They misrepresented the position that the company has taken through the course of negotiations. Their news release said that we were asking them to work for less money and in unsafe conditions, and that is absolutely inaccurate,” said O’Reilly spokesman Mark Merz. “Their news release was an attempt to force the company to give into their unreasonable demands.”

Twenty-three drivers deliver auto parts to most of O’Reilly’s 99 retail stores across Minnesota, from a distribution center in Brooklyn Park. The drivers have worked without a contract since Dec. 10, and have been in negotiations with the company since September.

Union officials said that talks went late into the night Thursday and resumed at 8 a.m. Friday. Both sides agreed early Friday to temporarily extend the contract until Jan. 27.

Merz said O’Reilly Auto has “been and will continue to be in good-faith negotiations” with the union. He said the company already agreed to increase drivers’ pay.

Teamsters business agent Troy Gustafson said the union has consistently complained that O’Reilly Auto’s driving team is understaffed.

“They have 23 drivers now when they theoretically should be at 27 or 28 for the amount of work they have,” Gustafson said. “They are growing and have been understaffed by three or four drivers for all but two months of the last six years. That puts more work and heavier loads on the existing drivers and keeps them on the roads longer at night. That creates unsafe working conditions.”

Gustafson said that O’Reilly Auto Parts also uses an unfair and complicated formula of “averages” that ultimately determines what a driver gets paid — and it doesn’t include overtime. It’s the formula that drivers want changed.

He noted that O’Reilly Auto Parts had record earnings in 2015 and increased sales and profits in each quarter in 2016.

O’Reilly Auto Parts is headquartered in Springfield, Mo., and operates 4,712 auto parts stores in 45 states. Revenue is expected to reach $8.5 billion to $8.6 billion this year, Merz said.