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HARRISBURG, Pa. (CBS/AP) — A six-term Democratic state representative from Philadelphia has died of a suspected heart attack.

The daughter of Rep. Mike O’Brien said he died in the early hours on Monday in the home where he had lived as a child in the city’s Fishtown neighborhood.

Bridget O’Brien says her father had been battling a host of medical issues.

The 64-year-old O’Brien had decided not to seek re-election this year. He had been the ranking Democrat on the Urban Affairs Committee.

Survivors also include his wife and son.

Mike O’Brien had been a legislative aide to his predecessor, and before that had worked in a meatpacking plant.

Tributes have poured from other lawmakers that have worked closely with, knew, or aspired to be like O’Brien.

“He was a great man,” wrote Rep. Ryan Bizzarro.

United States House candidate Dwight Evans also paid tribute to O’Brien after he learned of the news.

“Mike was a tireless advocate for those who felt their voices could not be heard,” wrote state Sen. John Sabatina.

“Another dear colleague gone too soon. May your soul rest at peace, Representative Michael O’Brien. Our thoughts and prayers to the family,” wrote Rep. Patty Kim in a tweet.

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)