About 4,000 janitors who clean Twin Cities office buildings could go on strike Feb. 14 if they haven't reached a contract agreement.

Members of the janitors union voted Saturday to authorize the strike, saying contract talks have stalled. The janitors' last three-year contract expired Dec. 31; talks for a new deal began in October.

"We need a contract by that day [Feb. 14], or we will strike," said Javier Morillo, president of Local 26 of the Service Employees International Union.

Local 26 represents janitors for cleaning companies, which in turn have contracts with office building owners. Most of its janitors work in downtown Minneapolis and St. Paul, though some are in office buildings scattered around the seven-county metro area.

The cleaning companies haven't formally responded to Local 26's wage offer, but have proposed measures that could lead to health benefit cuts, as well as the increased use of part-time workers, to the detriment of full-timers, Morillo said.

Full-time janitors make $14.62 an hour, while part-timers make $11 to $13 an hour, he said. The union has asked for initial wage increases of $1 an hour across the board, and has proposed raising part-timers' hourly pay to $15 an hour by the end of a new three-year contract. Local 26 has also proposed raising the number of sick days.

"The market has never been healthier — or at least not in a long time — for commercial real estate," Morillo said. "The building owners can afford to step forward for janitors."

John Nesse, spokesman for the Minneapolis-St. Paul Contract Cleaners Association, an employers group, said the union wants wage increases of 20 to 45 percent over the duration of the new contract.

Nesse declined to further discuss specifics, though he said employers will offer a wage increase "to reflect the reality of the market."

About 500 workers participated in the strike authorization vote Saturday. The vote was unanimous, Morillo said.

Sonae Cortez, a full-time janitor from St. Paul who works in a bank, voted to strike. "We have had many meetings with the companies and they don't want to give us raises," said Cortez, a member of Local 26 since 2008. "So we are ready to strike."