Democratic Congressman Edward Markey is planning to tour the state to formally kick off his candidacy for the U.S. Senate seat vacated by newly sworn-in Secretary of State John Kerry.

Markey will launch the tour with a rally Saturday in his hometown of Malden, followed by stops in Worcester and Springfield.

Markey had already announced he would seek Kerry's seat.

Markey, dean of the state's congressional delegation, said he'll highlight his long career in the House fighting against what he described as "big oil," the gun industry, polluters and others whom he said have harmed the lives of Massachusetts families.

Fellow Democratic Congressman Stephen Lynch has also announced his candidacy.

Massachusetts Republicans are scrambling to find their own candidate after former U.S. Senator Scott Brown opted out of the race Friday.