BOSTON -- Democratic U.S. Rep. Edward Markey said Friday he will not run for the seat of the late Sen. Edward Kennedy.

Markey has been in the House for 33 years and is chairman of an energy subcommittee. He said he decided not to run because he feels he can do more for the state in his current position in the House.

"I believe that my leadership positions and seniority in the House allow me to accomplish more for my Congressional District and for Massachusetts," Markey said.

Markey, of Malden, is the longest serving member of Congress from Massachusetts.

Massachusetts Attorney General Martha Coakley is the only Democrat to officially announce for the seat, though Congressmen Steven Lynch and Michael Capuano have both taken out nomination papers and signaled that they will run.