Several dozen janitorial workers from the Service Employees International Union (SEIU), including Sonya Cortez, center, a single mother of two who also cares for her 75-year-old mother, rallied Monday outside the Securian Center in St. Paul. (Star Tribune/The Minnesota Star Tribune)

No deal was reached Monday in contract negotiations between Twin Cities janitors and the cleaning companies that employ them, and the union that represents the janitors threatened another strike.

The janitors went on strike Feb. 17 for 24 hours, setting up picket lines across the metro area as they asked for higher wages and better working conditions. They returned to work the following day, but some of their allies protested in downtown Minneapolis and stopped traffic during rush hour the morning of Feb. 18.

Local 26 of the Service Employees International Union said that its negotiators had not reached a deal Monday and would meet again with representatives of the cleaning companies on Friday and Saturday.

"If no deal is reached this weekend, we will announce a new strike deadline," said Javier Morillo, president of Local 26.

John Nesse, an attorney representing the cleaning companies, said he was optimistic the two sides would make progress later this week.

Members of Local 26 work for cleaning companies who in turn have contracts with office building owners. Most of them work in downtown Minneapolis and St. Paul, but some are in office buildings scattered around the seven-county metro area.

The key cleaning companies negotiating with the janitors are ABM Janitorial Services, Marsden Building Maintenance, ABLE Building Maintenance and Harvard Maintenance.

Monday's was the 12th bargaining session between the two sides, which have been far apart on wages since bargaining began in November. Full-time janitors, who now earn $14.62 per hour, are asking for a $1 an hour raise each of the next three years.

SEIU negotiators have also proposed raising part-timers' hourly pay to $15 an hour by the end of a new three-year contract, and giving workers additional sick days.

The cleaning companies have offered a much more modest concession — to raise full-time workers' pay above $15 per hour by the beginning of 2018, but not part-time employees'.

Adam Belz • 612-673-4405 Twitter: @adambelz