The incumbent will face at least one opponent in the Democratic primary. Tanisha Sullivan, the president of the Boston branch of the NAACP, announced her bid last week.
The Democrat who was first elected to the Massachusetts House in 1975 could surpass the record of 28 years in the post if he wins an eighth four-year term this November.
Longtime Secretary of State William Galvin said early Monday morning that he will run for reelection this year, telling voters that he would like to continue the work he's done since 1995 at a time when "[t]he necessity of faithful election administration has never been more obvious."