By 1925, Withrow was selected by his union to serve as one of their lobbyists to the state legislature. Through his political activities, he also became a member of the La Follette Progressive Republican Committee of La Crosse County. In 1926, he won the Republican nomination for
Wisconsin State Assembly in
La Crosse County's 1st district (comprising most of the city of La Crosse). Withrow easily prevailed in the general election with 68% of the vote. During the
1927 legislative term, Governor
Fred R. Zimmerman, a stalwart Republican, sought to lower the income tax and offset the revenue by raising the
property tax. Withrow was a leader of the progressive resistance to those measures, describing it as an attempt to raise taxes on farmers to reduce taxes on wealthy business owners.
First election to congress In 1928, U.S. representative
Joseph D. Beck announced he would run for
Governor of Wisconsin rather than seeking another term in Congress. Withrow chose to abandon his Assembly re-election to enter the Republican primary to succeed Beck as representative of
Wisconsin's 7th congressional district. The progressive Republicans of the district quickly rallied around Withrow, but several other prominent politicians joined the race anyway, including
Merlin Hull, a former secretary of state who ran in the primary two previous times, and
Otto Bosshard and
Alexander Frederick, who had both served several terms in the Assembly. Withrow ultimately fell 2,300 votes short of Merlin Hull, who won the primary with 35% of the vote. Withrow ran again in 1930, launching a primary challenge against Hull. Withrow sought to emphasize his campaign as supporting farmers' interests against the business interests which he alleged were represented by his stalwart Republican opponent. This time there were no other candidates in the race; Withrow won the head-to-head primary against Hull with 52% of the vote. He faced only a Prohibition Party opponent in the general election, but Hull received a large number of write-in votes. Withrow prevailed with 82% of the vote. The
72nd Congress was one of the most closely divided in American history. Withrow and seven other Wisconsin progressive Republicans led a faction of holdouts which refused to help organize the House until Republican leadership agreed to several of their policy prescriptions for the
Great Depression. Their demands included support for unemployment and agricultural relief programs. However, the issue became moot as Democrats took the majority before Republicans could pass an organizing resolution. Due to the
Reapportionment Act of 1929, Wisconsin lost a congressional seat in reapportionment following the
1930 United States census. This resulted in a significant redrawing of Wisconsin's congressional districts. Under the new plan, passed during a special session of the
1931 legislature, Withrow resided in
Wisconsin's 3rd congressional district—roughly the southwest quadrant of the state. In the new district, Withrow faced another difficult primary against a stalwart Republican opponent, Charles A. Dittman. Withrow prevailed with 58% of the vote. In the 1932 general election, a Democratic wave saw Republicans lose 101 seats, but Withrow easily defeated his Democratic opponent, attorney
John J. Boyle. During the
73rd Congress, Withrow supported several of the new initiatives of Democratic president
Franklin D. Roosevelt. In the midst of the
1934 West Coast waterfront strike, Withrow led a successful bipartisan effort to bring a vote on a 30-hour work week for railroad employees, gathering enough signatures on a
discharge petition to force a vote on his bill. But the House Committee with jurisdiction then voted to report the bill without their recommendation, which effectively killed it.
Progressive party In May 1934, the
Wisconsin Progressive Party officially split from the
Republican Party of Wisconsin after three decades of bitter primary battles and intra-party feuding. Withrow did not attend the Progressive Party's organizing convention, but said he would poll his constituents and abide by their sentiment as to the split. Withrow formally announced in July 1934 that he would run for re-election on the Progressive Party ticket. In the 1934 election, Withrow easily won his third term in Congress, defeating Republican
Levi H. Bancroft and Democrat Bart E. McGonigle. He won re-election again in 1936 with 51% of the vote. Withrow chose to run again for the seat in 1940, but lost a close election to Republican
William H. Stevenson. Throughout the 1942 campaign, he made significant efforts to distance himself from past
isolationist positions and criticized his Republican rival for his votes against pre-war preparedness policies. Withrow fell short again in another close election; Stevenson winning the election with 47% of the vote. He also served as a mediator in labor disputes. In 1946, the Progressive Party disbanded with the majority of delegates voting to return to the Republican Party. Withrow followed that move and rejoined the Republican Party. He ran for
sheriff of La Crosse County that fall, but lost the primary to Vernon H. Lamp.
Return to congress Undeterred by four straight election losses, Withrow announced in 1948 that he would launch a
primary challenge against William H. Stevenson to reclaim the 3rd congressional district seat he had previously represented. His campaign announcement listed a number of political grievances against Stevenson, saying he had been silent on the economic pain of his constituents and the problems faced by organized labor, and again criticized Stevenson for isolationist votes and their potential economic impact in Wisconsin. Withrow prevailed by about 1400 votes in the Republican primary, and went on to an easy victory in the general election. He faced another difficult primary in 1950, against state senator
Foster B. Porter and businessman Joseph F. Walsh. Withrow survived by just 879 votes, receiving 36% in the primary. Nevertheless, Withrow still won a substantial victory in the general election over Democratic nominee
Patrick Lucey. William H. Stevenson returned for a rematch in the 1952 Republican primary, but Withrow prevailed again in another close election. In 1958, Withrow was involved in a controversy due to his association with Dominican dictator
Rafael Trujillo. Withrow was counted among Trujillo's defenders in Congress at a time when he was receiving American aide and his political enemies were dying mysterious deaths in the United States, but no illicit relationship was ever alleged or proved. Throughout his career, he remained a progressive Republican; he voted in favor of the Civil Rights Acts of
1957 and
1960. In October 1959, Withrow announced that he would retire at the end of the
81st Congress. ==Personal life and family==