MARBLEHEAD – A Marblehead man and former aide to Gen. David Petraeus in Iraq is considering running for Congress as an independent challenger to U.S. Rep. John Tierney, a Democrat from Salem, and Republican Richard Tisei in the 6th Congressional District.Seth Moulton, a 33-year-old veteran of the Marine Corps, told The Daily Item on Tuesday that he is “seriously looking” at announcing his candidacy in one of the most hotly contested races in Massachusetts this year.”I truly believe in the importance of public service,” Moulton said when reached by phone in Washington, D.C.Moulton is a 2011 graduate of the Harvard Kennedy School for public service and Harvard Business School. He was born and raised in Marblehead, attended the prestigious Phillips Academy in Andover for high school and received his undergraduate in 2001 from Harvard.Moulton joined the Marines in 2001, where he served in Iraq first as an infantry officer, then a platoon commander and finally a special assistant to Petraeus, who is currently the director of the Central Intelligence Agency and who was then the commander of training, equipping and organizing the Iraqi security forces.Moulton declined to comment on why he is considering getting into the race this late in the campaign, but he did say he would likely run as an independent who would caucus with the Democrats.Moulton also declined to comment on any issues he would champion during the campaign.”I’m obviously an outsider,” he said, when asked about the uphill battle he would face if he decided to run.He said coming into the race as a virtual unknown could be an advantage.”I think a lot of people think that maybe something, some different perspectives [are a good thing],” he said.Moulton said he expects to make a decision in the next few days.Moulton is related to Cyrus Moulton, a reporter with The Daily Item.Amber Parcher can be reached at [email protected].