As a Senator, he strongly opposed American military involvement in world affairs, being derided by his opponents as an isolationist.

By 1920, Langer was publicly accusing Townley of Bolshevism, and failed in a primary campaign to replace the incumbent NPL governor Lynn Frazier as the party's gubernatorial candidate.

Langer's break with the NPL leadership was a reflection of the infighting that limited the party's eventual influence on North Dakota politics.

As governor, Langer in 1933 required all state employees to donate part of their annual salaries to the NPL and to the Leader, a weekly newspaper owned by high-ranking officials in his administration.

The trial was presided over by Judge Andrew Miller and prosecuted by Lanier, two of Langer's strongest political opponents in the state.

[5] He eventually relented when his own officers refused to recognize his authority, and Olson served the remainder of Langer's term as governor.

Miller, following a recusal motion by Langer, refused to step down as judge in the first retrial, which resulted in a hung jury.

This trial, unprecedented on perjury in an affidavit requesting a recusal, resulted in a directed verdict to acquit Langer.

[11] Biographer Glenn H. Smith calls Langer's Senate career "A Study in Isolationism, 1940–1959" and emphasizes his close ties with German American and Scandinavian American voters who bitterly remembered the First World War in the Dakotas and deeply distrusted Britain and the United Nations.

[12] Like Senator Henrik Shipstead of Minnesota, Langer championed non-interventionism[13] and supported minimizing America's involvement in World War II.

At home, he concentrated on making life easier for North Dakotan farmers by raising wheat prices and granting government relief.

[16] In September 1950, Langer filibustered to prevent the override of President Harry S. Truman's veto of the McCarran Internal Security Act for five hours before collapsing.

[17] In 1951, Langer lobbied John J. McCloy, the U.S. High Commissioner for Germany, to grant a reprieve to Martin Sandberger, a high-ranking SS official who had been convicted of crimes against humanity and war crimes for his role in the mass murder of Jews and others in Estonia during the Holocaust.