MOUNT LAUREL, N.J. — Shortly after signing with the San Diego Chargers, Jon Runyan announced he'll retire at the end of the season and run for Congress in New Jersey.

The 35-year-old offensive lineman said in a statement late Tuesday that he told Republican officials in Burlington County of his plans to challenge Democratic Rep. John Adler in New Jersey's 3rd District.

"I look forward to a successful end to my career on the field," Runyan said, "and a spirited campaign against Congressman Adler in 2010."

Runyan, who was signed as a free agent Tuesday, hasn't played since the end of last season. He wasn't re-signed by Philadelphia after having surgery on his right knee.

Runyan has not given interviews about his political ambitions or said much about his stance on issues. A previous statement mentioned the country was being taken in the wrong direction by career politicians "incapable of solving the problems we face."

The seat was held for more than two decades by Republican Jim Saxton, who retired last year.

Adler, who replaced him, is seen as vulnerable. He was a popular state senator, but is a Democratic first-term representative in a district that traditionally supports Republicans.

Adler voted against a health care overhaul bill this month, rousing opposition from the left. Adler's chief of staff, Jill Greco, said the Congressman is "not thinking about partisan politics or next year's election."

Runyan, who played 13 seasons in the NFL for Houston, Tennessee and Philadelphia, was one of the more popular Eagles. He never missed a game in nine years with the Eagles, starting 192 straight regular-season games.

Parts of three counties make up the 3rd District, which stretches from the Philadelphia suburbs to the shore. Runyan lives in Mount Laurel, N.J.