He became an assistant to Texas Attorney General James Burr V Allred in 1931 and specialized in prosecuting major oil companies.

After serving in the United States Army during World War II, Yarborough repeatedly ran for governor, opposing the conservative faction of Democrats led by Allan Shivers.

He won election to a full term in 1958 and was reelected again in 1964, defeating Harris County Republican Party Chairman George H. W. Bush in the latter race.

Yarborough was known as "Smilin' Ralph" and used the slogan "Let's put the jam on the lower shelf so the little people can reach it" in his campaigns.

[12][1] He spent one year working and studying foreign trade and international relations in Europe, mostly as assistant secretary for the American Chamber of Commerce in Berlin, Germany.

Texas Secretary of State John Ben Shepperd resigned in the spring of 1952 and was elected attorney general that year.

After being endorsed by former opponent and former Governor W. Lee O'Daniel, and making aggressive attacks on the Shivers-backed candidate, Yarborough looked to win the runoff, but instead he trailed Daniel by about nine thousand votes.

Yarborough won the special election with 38 percent of the vote to join fellow Texan Lyndon B. Johnson in the Senate.

Yarborough's first major legislative victory was the successful passage of the National Defense Education Act of 1958, which began federal funding of loans and grants to universities and their students.

[15] In the 1958 Democratic primary, Yarborough easily defeated the conservative William A. Blakley, a millionaire businessman from Dallas who was backed by Daniel.

Blakley had been the interim senator from January to April 1957 but did not run in the special election in which Yarborough defeated Dies and Hutcheson.

In the nationally Democratic year of 1958, Yarborough cruised to victory in the general election over the Republican nominee, publisher Roy Whittenburg of Amarillo.

During his first full term, Yarborough worked for a bill signed by President John F. Kennedy to designate Padre Island as a national seashore.

From the start of the President's tour of Texas, Yarborough considered that he had been slighted by some of the arrangements and so, in the early stages, refused to ride with Johnson, despite repeated pleas by Youngblood.

[16] Then, during the short flight from Fort Worth, Kennedy persuaded Connally to give Yarborough a more prominent role in some of the later functions planned in Austin.

[24] Shortly after the passing of the Civil Rights Act of 1964, on July 9, Johnson nominated former Florida governor LeRoy Collins to a position in the Community Relations Service, which was designed to mediate racial disputes.

Strom Thurmond, the most senior southern member of the Commerce Committee, bitterly opposed Collins's nomination, based on a speech that Collins made in Thurmond’s home state in which he said that southern leaders’ “harsh and intemperate” language unnecessarily stoked racial unrest.

Thurmond, aware of Magnuson's struggles, stationed himself outside of the committee door, physically blocking any entry by later-arriving senators.

The only southern senator to have voted for the Civil Rights Act, Yarborough joked to Thurmond, "Come on in, Strom, and help us get a quorum."

His Republican opponent was George H. W. Bush, who attacked Yarborough as a left-wing demagogue and for his vote in favor of the Civil Rights Act of 1964.

Yarborough denounced Bush as an extremist to the right of that year's GOP presidential nominee, Barry Goldwater, and as a rich easterner and carpetbagger trying to buy a Senate seat.

It has since been learned that then-Governor Connally was covertly aiding Bush, against President Johnson's wishes, by teaching Democrats the techniques of split ticket voting.

Yarborough supported Robert F. Kennedy for president until his assassination, then Eugene McCarthy until his loss in Chicago, finally backing Hubert Humphrey in his 1968 campaign against Nixon.

Bentsen played on voters' fears of societal breakdown and urban riots, made an issue of Yarborough's opposition to the Vietnam War, and called him a political antique.

The University of Texas at Austin Press published a biography, Ralph W. Yarborough: The People's Senator, by Patrick L. Cox.

[33] In October 1966, Yarborough introduced Senate Bill 5–3929 to establish a 75,000-acre national park to preserve the remaining natural and undisturbed areas of the Big Thicket in southeast Texas.

[35] The next year, he voted for the National Aeronautics and Space Act, citing the impact he believed the agency could have on his hometown of Houston.