Massachusetts Democratic Rep. Michael E. Capuano announced Tuesday that he will not run in the Senate special election to fill the seat expected to be vacated by Democrat John Kerry.

Capuano’s colleague, Democratic Rep. Edward J. Markey, is the only declared candidate, and he has worked to clear the Democratic field. Kerry is expected to soon be confirmed as the next secretary of State. The Democratic Senatorial Campaign Committee and Kerry, among others, support Markey’s bid.

“After careful consideration, I have decided not to enter the race for US Senate,” Capuano said in a statement. “Instead, I look forward to focusing on the important issues facing the new Congress. My current work in the House and whatever opportunities the future may hold, afford me the greatest honor of my life, fighting for the Citizens of the Commonwealth.”

Stephen F. Lynch, another Bay State Democratic congressman, has said he is considering a run, as has a local rabbi, Jonah Pesner. Capuano ran in the 2009/2010 Senate special election after death of Democratic Sen. Edward M. Kennedy. He finished second in the Democratic primary, taking 28 percent of the vote.

Former Bay State Sen. Scott P. Brown, who won the 2010 contest, has not yet said whether he’ll run in the special election. Brown is considered the only Republican who could make the race competitive.