The Portland Community Chamber of Commerce is expected to endorse former state Sen. Ethan Strimling for mayor, according to the Strimling campaign.

The announcement is the latest in a string of endorsements for Strimling, who along with Green Independent Party leader Tom MacMillan is challenging incumbent Mayor Michael Brennan.

Brennan has been running on his record of accomplishment and often notes how unemployment has dropped over the past four years. He also highlights his participation in the city’s business visitation program.

Brennan edged Strimling in the 2011 mayoral election. That year, the chamber listed Strimling as “worthy of mention” in the ranked-choice election that drew 15 candidates in all.

Strimling’s campaign said the endorsement will be announced on Tuesday at a news conference at the Old Port Wool and Textile Co. on Danforth Street.