n 1974, he won the Democratic nomination for the Senate seat being vacated by 20-year Republican incumbent Norris Cotton. He lost to Republican Congressman Louis Wyman by 355 votes in the November 5 election. However, Durkin demanded a recount, which resulted in him winning by 10 votes. Governor Meldrim Thomson then certified Durkin as the winner. However, Wyman demanded another recount, in which he prevailed by only two votes. Cotton resigned on December 31, 1974; Thomson appointed Wyman to the seat for the balance of the term ending January 3 1975 to give him a leg up in seniority. This appeared to end the dispute, but Durkin appealed to the full Senate, which is the final arbiter of Senate elections per the Constitution. The Senate Rules Committee, which has jurisdiction over elections, deadlocked on whether to seat Wyman for the 1975-1981 term pending the resolution of the dispute. On January 14, the Senate returned the matter to the Rules Committee, which returned 35 disputed points to the full Senate based on 3,000 questionable ballots. However, the Senate was unable to break a deadlock on even one of the 35 points. After seven months of wrangling which included six unsuccessful Democratic attempts to seat Durkin, Wyman proposed that he and Durkin run again in a special election. Durkin agreed, and the Senate declared the seat vacant on August 8, 1975 pending the new election. Thomson appointed Cotton to his old seat in the meantime. The special election was held on September 16, and Durkin won handily, defeating Wyman by 29,000 votes – ending what remains the longest vacancy following the most closely contested direct Senate election in history. For the first four years of his term, Durkin served alongside fellow Democrat Thomas J. McIntyre. New Hampshire hadn't been represented by two Democratic Senators since before the Civil War. He was defeated for re-election in 1980 by Warren Rudman and resigned six days before the end of his term. He sought the state's other Senate seat in 1990, but was defeated handily by Republican Congressman Bob Smith.