Rep. Patrick Kennedy has decided not to seek re-election after eight terms in Congress, saying his life is “taking a new direction” just months after the death of his father and mentor, Sen. Edward Kennedy.

The Rhode Island Democrat taped a message with his decision to be aired on Rhode Island’s television stations Sunday night. The Associated Press viewed the message Thursday, ahead of the announcement.

The decision comes less than a month after a stunning upset by Republican Scott Brown in the race for the Massachusetts Senate seat his father held for almost half a century. Last week, as Brown was sworn into the seat, Patrick Kennedy called Brown’s candidacy a “joke” and predicted Brown would betray his union supporters.

Kennedy did not give a reason for his decision, but he began the message by saying it had been a difficult few years for many people, then segued into the death of his father.

He remained committed to public service, and he thanked Rhode Island voters for supporting him through ups and downs.

He has been in and out of treatment for substance abuse since crashing his car outside the U.S Capitol in 2006. Still, he has been comfortably re-elected twice since then, after making mental health care his signature issue in Washington.

Kennedy was not specific about his plans, but said he would continue to fight for issues including on behalf of those suffering from depression, addiction autism and post-traumatic stress disorder.

The only Republican in the race, state Rep. John Loughlin, has been working with Brown’s campaign team, the Shawmut Group, and was raising money. But Kennedy was heavily favored to win the race: Registered Democrats outnumber Republicans more than 4 to 1 in Rhode Island. Loughlin has little statewide recognition, and Kennedy had four times as much campaign cash on hand coming into the year.

“We hope that wherever life takes him beyond his career in Congress that he has good fortune,” Loughlin said. “And we’re going to stay in the race.” – No Democrat has entered the race for the seat!