Victor L. Berger (1860–1929) was the first socialist ever elected to the U.S. Congress. He represented a district in Milwaukee, Wisconsin, and was a founder of the Socialist Party of America. Wisconsin Historical Society+1

Berger was born in Austria-Hungary and immigrated to the United States in 1878. He became a teacher, newspaper editor, and labor activist before entering politics. He believed that socialism should be achieved through elections and gradual reform rather than violent revolution. Wisconsin Historical Society+1

His ideas included:

Berger became associated with what was called "sewer socialism." Despite the unusual name, it referred to practical local government. Milwaukee's socialist leaders focused on clean water, modern sewer systems, parks, schools, and honest, efficient city government rather than revolutionary politics. Wikipedia+1

During World War I, Berger opposed U.S. involvement in the war. He was convicted under the Espionage Act of 1917 for his anti-war statements, and although he was elected to Congress, the House refused to seat him. In 1921, the Supreme Court of the United States overturned his conviction, and he later returned to Congress. Wikipedia+1

One important point is that Berger's legacy is mixed. Although he advocated economic reforms that later became mainstream, historians have also documented that he held racist views early in his career and supported restrictions on Asian immigration. Later in life, some of his views on race became more moderate, but those earlier positions remain an important part of how historians evaluate him today. Wikipedia

As for democratic socialism, it is different from communism. Democratic socialists seek to achieve greater economic equality through democratic elections while preserving political freedoms such as free speech, free elections, and a multiparty system. They generally support a mixed economy, with both private businesses and government involvement in areas such as health care, education, or public utilities. Berger was one of the earliest and most influential advocates of that approach in the United States.