US Senator. He served in the United States Senate as a Republican. Following the resignation of Senator William Kenyon, he was elected and served from November 8, 1922, to March 3, 1925. After the November 1924 election, he continued to serve from March 4, 1925, and until April 12, 1926, when he was succeeded by Democrat Daniel F. Steck, who successfully contested Brookhart's election, charging illegalities at the polls with two disputed ballot counts. With the Iowa Republican Party no longer supporting Brookhart, allegedly "for the manipulations of his own party," Steck was pronounced the winner and was seated in the Senate after a seventeen-month delay. Following this bitter unseating by the Senate, he was elected to the Senate as a Republican in 1926 and served from March 4, 1927 to March 3, 1933. As an Independent, he was an unsuccessful candidate for renomination for the November 1932 election. He was a candidate for the Senate in 1920 but did not unseat the long-time incumbent. Born in a humble cabin, one of ten children of a poor farmer, he attended rural schools and one year of high school. "Brook," as he was called, was educated at Southern Iowa Normal School with an emphasis in scientific courses. For five years, he taught school while also reading the law and was admitted to the bar in 1892 and began practicing in Washington County. Entering politics, he served six years as county attorney. He was not a successful court attorney. During the Spanish-American War and World War I, he served in the army, reaching the rank of lieutenant colonel. In 1912, he was the captain of the United States rifle team, which earned the title of the world's champion. As a rifle instructor for the Iowa National Guard, he concluded that alcohol and guns were incompatible. He was a supporter of prohibition. He quantified the accuracy harms associated with mild beer, saying it lowered accuracy by 7%. With that information, he convinced the Governor of Iowa to make the rifle range "bone dry." He was the president of the National Rifle Association from 1921 to 1925. After Brookhart's time in the U.S. Senate, he was a special advisor on Soviet trade for the federal agency of the Agricultural Adjustment Administration until 1935. After leaving government service, he practiced law in Washington, D.C.