Office workers across the Twin Cities could find their cubicles a mess if thousands of janitors hit the picket line.

Members of the union representing more than 4,000 janitors who clean most of the metro area's commercial office buildings voted Saturday to authorize a strike.

The vote gave the bargaining committee for the Service Employees International Union's Local 26 a green light to call a strike at any time.

The vote, by nearly 500 members of the union, was close to unanimous, said spokesman David Zaffrann.

The janitors, whose contract expired Jan. 8, are scheduled to hold a bargaining session this week with the Minneapolis-St. Paul Contract Cleaners Association.