Having served as Governor of New York State between 1933 and 1942, in 1949, at the age of 71 Lehman was elected United States Senator to fill the unexpired term of Robert F. Wagner, Sr. Reelected for a full term in 1950, Senator Lehman gave six years of distinguished service to the people of his state and nation.
His courage, moral integrity and unfaltering dedication soon made Senator Lehman one of Washington's most respected senators; just as they had won him affection and honor in New York and on the world scene. He became known as "the conscience of the Senate" as he led those who stood for liberal principles and for the rights of accused individuals in the early 1950s when Senator McCarthy's influence was at its peak. Utterly fearless and disdainful for his own political fortunes he fought, at times almost alone, against tremendous opposition.
He was among the most vigorous fighters for bills protecting the civil rights of members of minority groups. He also led the battle against discriminatory national quotas in the immigration laws.
Just as Governor Lehman in the 1930s in the state of New York had been in the forefront of every struggle to expand Social Security, to develop public housing and public power, and to protect natural resources and the rights of the people, so as Senator in the 1950s he fought for similar legislation on the national scene. In international affairs the Senator and former Director General of UNRRA spoke and voted in favor of every effort to protect world peace through the United Nations.