Senator Robert Wagner, 1934
Wagner represented New York in the Senate between 1927 and 1949. An ardent New Dealer, he is most well known for sponsoring the National Labor Relations Act (popularly known as the Wagner Act). This landmark legislation put severe limits on anti-union activity by employers, forced employers to bargain in good faith with unionized workers, and created the National Labor Relations Board to oversee that bargaining.
For all intents and purposes, this was the federal government encouraging workers to take their lives in their own hands and form a union. I cannot stress strongly enough how revolutionary the Wagner Act was. The government had been an active, hostile agent against labor unions from at least the 1820s and 1830s. During the late nineteenth and early twentieth centuries, both state and federal governments served as private strikebreaking forces for companies. Meanwhile, workers suffered and died trying to improve their lives. Wagner's shepherding of this act through Congress is not only a highlight of the New Deal, but one of the greatest single acts ever accomplished by a senator. The National Labor Relations Act materially improved the lives of millions of Americans, gave workers hope instead of forcing them to turn to revolution in desperation during the Great Depression, and helped pave the way for America's post-war prosperity.
He also sponsored other successful pro-worker legislation, as well as pioneering legislation for the disabled, such as the Wagner-O'Day Act, which provided for a variety of services for the blind.
Wagner's legacy extends much farther than one bill. He also sponsored anti-lynching legislation in the Senate; of course, Southerners never allowed this to pass. He sponsored pioneering public media legislation; an amendment to the Communications Act of 1934 would have given 1/4 of all radio stations to non-profits. This did not pass either. Another unsuccessful piece of legislation he worked to pass was the Wagner-Rogers bill of 1939 which would have allowed Jewish children to become refugees in the United States. This was defeated by an anti-Semitic Congress.
One of the hallmarks of a successful senator is the ability to get legislation through the system. While Wagner was unsuccessful in many of his endeavors, the National Labor Relations Act alone makes him a truly great leader in the history of the Senate.