Michael Flaherty, a South Boston native who began his political career in the mid-1990s as an upstart challenger to entrenched incumbents of an earlier generation, will not seek re-election to the Boston City Council this year. Flaherty made the surprise announcement via a statement posted to social media platforms on Wednesday evening.

Flaherty's decision surprised most everyone, since he was already certified and guaranteed a spot on the ballot this fall. However, Flaherty still has time to withdraw his name from the ballot— which will leave just eight candidates vying for one of four at-large spots on the 13-member council. The other nine councillors are elected to district seats.

Flaherty said he would finish the rest of his term in office, which ends in January.

Flaherty has served ten terms in office, making him the most senior member of the body. He ran for mayor in 2009 as a challenger to Mayor Thomas M. Menino. After his defeat in the election, Flaherty left the council for two years to practice law exclusively before he voters returned him to his at-large post in 2013.

Flaherty was first elected in 1999, dislodging longtime incumbent Albert 'Dapper' O'Neil from his citywide seat.

"While this decision will come as a surprise to many," Flaherty wrote, "I reached it after much deliberation and self-reflection over the past few months, and in close consultation with my wife and family. By the end of this year, I will have served on the City Council for twenty years. I believe I have served the city of Boston and its residents faithfully and effectively during my tenure, but it is now time to turn the page and move on the next chapter of my life."

Flaherty said he has not "present plans for run for another public office."

His decision to withdraw from the council race means there will not be a preliminary election in September.

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