PORTLAND — A former state legislator from Portland has announced his candidacy for mayor.

Michael Brennan, who has served in the Maine House and Senate and currently teaches at the Muskie School of Public Service, joins a field that already includes seven candidates. The others are Erick Bennett, Charles Bragdon, Jodie Lapchick, David Marshall, Jed Rathband, Christopher Vail and Zouhair Bouzrara.

Candidates can’t start circulating petitions to get on the ballot until July. Once they register, however, they can set up candidate committees, raise funds and take other steps to prepare for the race.

Ballot petitions require at least 300 signatures and must be returned by Aug. 29.

A former Senate majority leader, Brennan ran for Congress in 2008 and finished third in the Democratic primary won by U.S. Rep. Chellie Pingree.