He narrowly defeated state legislator Philip W Johnston of Marshfield by just 119 votes[9] after a recount, which was conducted in a handful of contested towns.

[12] On March 4, 2010, The Boston Globe confirmed that Delahunt would retire that year rather than seek reelection for an eighth term.

[13] Shortly before the announcement of his retirement, it was discovered that Delahunt, while serving as district attorney for Norfolk County, Massachusetts, had refused to file charges against Amy Bishop for shooting and killing her brother in 1986.

[17] The program, which has since been expanded to help 500,000 people across the U.S., was carried out via the Venezuelan owned Citgo,[18] and brought accusations that Delahunt was assisting an anti-American leader.

[19] In the 110th U.S. Congress, Delahunt served as the chair of the United States House Foreign Affairs Subcommittee on International Organizations, Human Rights, and Oversight.

[16] Upon Delahunt's retirement, he formed the Delahunt Group,[23] a lobbying firm ("multi-service consulting firm focused on Government Affairs, International Market Entry Strategies, Corporate and Development Advisory, Federal and State Funding, and Appropriations, Regulatory and Permitting Assistance, Public Policy Strategies and Public Relations").

"[24] Less than two months after leaving Congress, Delahunt lobbied on behalf of the Wampanoag people in Massachusetts to help them secure Indian gaming rights with the state legislature.

Delahunt received over $15,000 in campaign contributions from the Wampanoag and Abramoff prior to leaving office sparking criticisms from good government advocates and casino opponents.

[27] Prime Policy Group's clients include companies like Accenture,[28] which have been criticized for moving offshore to avoid paying U.S. taxes.

This partnership dovetails with Delahunt's work on behalf of the Wampanoag as their primary backers are the Malaysian gambling giant Genting Group.

The Wampanoag venture, if approved, would give Genting a tax-free foothold in Indian gaming in the United States.

[31] Delahunt supported the creation of medical marijuana dispensaries to thwart the rise in prescription drug abuse.

While Congress was in session, Delahunt lived in a rented house with fellow Democratic politicians George Miller, Chuck Schumer, and Richard Durbin.