belief that it would make their holdings more valuable. As a result of this view, in 1896, Mantle joined the Silver Republican Party and became its chairman in Montana. He was an unsuccessful candidate for reelection to the Senate in 1899. In 1900, he returned to the Republican Party. Another Mantle cause in the Senate was protecting Montana timber interests. In 1897, outgoing President Grover Cleveland withdrew six million acres of forest land from the public domain to be set aside as a timber reserve. In Mantle's view, this move threatened Montana's mining interests, which depended on timber when opening and expanding mines. He also viewed Cleveland's move as a threat to Montana logging companies, since removing the land from public domain prevented them from harvesting trees for production of wood and paper products. After William McKinley succeeded Cleveland, he reduced the size of the timber reserve by more than 700,000 acres. Later life After leaving the Senate, Mantle resumed his business interests. With partner Charles S. Warren, he held ownership stakes in the Silver Bow Electric Company, commercial real estate, mines, insurance companies, and publishing houses. He was a noted civic activist, and his memberships included the Masons, Elks, Knights of Pythias, and the Rocky Mountain Club of New York City. In 1901, Mantle was again a candidate for the U.S. Senate. Both seats were up for election, and former Senator William A. Clark was chosen for one. Mantle was a major candidate for the other, but after the legislature was deadlocked for over a month, Republican legislators decided to back Thomas H. Carter, who lost to Democrat Paris Gibson. In 1902, Mantle was a delegate to the state Republican convention, and he was chairman of the state party's 1904 convention. He was also a delegate to the 1904 Republican National Convention, which unanimously nominated Theodore Roosevelt for a full term as president and Charles W. Fairbanks for vice president. He declined the party's nomination for governor in 1904, but accepted election as the state Republican Party chairman. In that fall's election, his efforts led Republicans to victory in the down-ballot statewide races, but Democrats won the governorship and lieutenant governorship. In 1902, the Montana Legislature named Mantle to the commission responsible for the state's participation in the 1904 Louisiana Purchase Exposition in St. Louis and 1905 Lewis and Clark Centennial Exposition in Portland, Oregon. The commission chose Mantle