Connell first rose to local political prominence in 1884 when he began giving speeches in support of presidential candidateGrover Cleveland. He was a perennially unsuccessful candidate in the 19th century. He failed to be elected over John H. Ketcham to the 55th United States Congress in 1896 or to the New York State Assembly in 1898 and 1900. After repeated failures, Connell attempted to curry favor with schoolchildren in the hopes that they would vote for him when they came of age. Between his campaigns, Connell served as police commissioner of Poughkeepsie for three years beginning in 1892, Dutchess County's inheritance tax appraiser from 1907 to 1909 and delegate to the Democratic National Convention in 1900 and 1904. In 1910, Connell and Hyde Park resident Franklin D. Roosevelt embarked on a joint campaign in the Hudson Valley in Roosevelt's Maxwell automobile; Connell was running for the U.S. House of Representatives and Roosevelt for the New York State Senate. From Connell, Roosevelt would borrow the opening phrase with which he would begin many speeches for the rest of his career: "My friends." Connell defeated the incumbent, ReupblicanHamilton Fish II, by 517 votes to win election to the 62nd United States Congress. In his brief time in Congress, Connell collaborated with Representative Isaac R. Sherwood in championing a successful Civil War veterans' pension bill. He had been nominated in 1912 as the Democratic candidate for reelection to the 63rd United States Congress.
Connell and his wife Mary had four children, Mary, Anne, Catherine and Richard. The younger Richard, who was his father's secretary during sessions of Congress, would go on to become an accomplished writer best known for his short story "The Most Dangerous Game." Connell was a member of the Royal Arcanum, Knights of Columbus and Order of Elks. Connell spent the night of October 29, 1912 making speeches in Putnam County and returned home to Poughkeepsie around 2:00 a.m. When he did not get out of bed the following morning for an 8:00 a.m. car which was hired to bring him to meet constituents in Middletown, his wife found him unresponsive. He had died in his sleep of heart disease. He is buried in St. Peter's Cemetery in Poughkeepsie.