Tierney has held the congressional seat for the sixth district, which includes the North Shore and Cape Ann, since 1997, and has said he is "pondering" a run.
Strengths: A strong progressive voting record: 100 percent liberal ratings from Americans for Democratic Action from 2001-2006 and 2008.
Weaknesses: Tierney's district could be eliminated if Massachusetts loses a congressional seat in the census, and he may want to preserve his financial resources for a redistricting election.
Tierney talked with an aid in his district office in December of 2000.
John Blanding/Globe staff