Kean became involved in politics at a young age. In 1905, His uncle got him appointed as a U.S. Senate page so he could observe the Inauguration of President Theodore Roosevelt. He attended the 1912 Republican National Convention, where he was escorted by his uncle's secretary, Donald H. McLean, with whom he would late serve in Congress. Young Kean was a Roosevelt supporter, although his uncle and father had publicly endorsed the incumbent President, William Howard Taft. After he returned from the war, Kean took on campaign responsibilities on behalf of his father, who was the Republican National Committeeman from New Jersey from 1918 to 1928. He was heavily involved in his father's successful campaign for the U.S. Senate in 1928, and his unsuccessful 1934 re-election bid.