Rep. John Tierney (D) announced Monday morning that he will not run in the Massachusetts Senate special election. The seven-term Democrat’s move sets the field for the special election, with Attorney General Martha Coakley, Reps. Mike Capuano and Stephen Lynch expected to run in the Dec. 8 Democratic primary to succeed the late Sen. Edward Kennedy (D).

“A great number of people have kindly urged me to run for the United States Senate,— Tierney wrote in a letter to supporters provided, which was provided by his campaign office. “I have given the matter serious consideration and determined that, at this time, I can best be of service in the U.S. House of Representatives — continuing to work to make education more affordable and accessible, to build and strengthen our nation’s workforce, to enact meaningful health care reform and to ensure we have a pragmatic foreign policy.—

State Sen. Scott Brown also announced his campaign over the weekend, although the Republican is expected to have an uphill battle in Massachusetts, a Democratic stronghold. The special election is scheduled for Jan. 19.