U.S. President George H.W. Bush shakes hands with Agriculture Secretary Clayton Yeutter at the White House in 1989. At left is Senate Minority Leader Robert Dole (R-Kan.) (Scott Applewhite/Associated Press)

Clayton Yeutter, a blunt-talking Nebraska farmer and head of the Chicago Mercantile Exchange who advocated for free markets while serving Republican administrations as U.S. trade representative and secretary of agriculture, died March 4 at his home in Potomac, Md. He was 86.

The cause was metastatic colon cancer, said his wife, Cristena Bach Yeutter.

In addition to his Cabinet-level jobs overseeing trade and agriculture in the 1980s and early 1990s, Dr. Yeutter served brief stints as chairman of the Republican National Committee and as President George H.W. Bush’s chief domestic policy adviser.

Dr. Yeutter, who had a law degree as well as a PhD in agricultural economics, derived considerable political influence from his unassailable party loyalty, his skill as a pragmatic negotiator and his formidable knowledge of agriculture policy. He had grown up in the Depression during the Midwestern dust bowl, was once named one of the country’s outstanding animal husbandry graduates, and operated his family’s 2,500-acre cattle and corn farm in central Nebraska.

He had, the New York Times reported, the “voice of a hog caller,” and was sometimes described as aggressively candid in his manner. In 1987, he sparked a diplomatic furor amid open-trade negotiations between the United States and Canada.

President Ronald Reagan is flanked by U.S. Trade Representative Clayton Yeutter, left, and President-elect George H.W. Bush, in 1988. (Dennis Cook/AP)

“I’m prepared to have American culture on the table and have it damaged by Canadian influences after the free-trade agreement,” Dr. Yeutter, then serving as chief U.S. trade negotiator, said at the time. “I hope Canada’s prepared to run the risk, too.”

Prime Minister Brian Mulroney said at the time that Dr. Yeutter was “stunningly ignorant” of Canadian sensitivities and fears regarding the accord with its southern neighbor and its potential effect on Canadian cultural identity.

The agreement moved forward anyway, and Mr. Yeutter was said to have remained in the Reagan administration’s good graces, having benefited from a strong rapport with Treasury Secretary James A. Baker III, among others in the president’s inner circle.

Dr. Yeutter (rhymes with “fighter”) began his political rise in 1966 helping to elect Norbert Tiemann (R) as Nebraska governor and serving as his chief of staff for two years. In 1972, he served as Midwest regional director of President Richard M. Nixon’s reelection campaign, while also climbing within the Agriculture Department ranks.

As assistant secretary of agriculture for international affairs, he helped persuade the European Economic Community to withdraw for the first time some of its agricultural subsidies in what was dubbed the “cheese war.”

“It made some of the Common Market’s agricultural ministers very unhappy,” he later said.

He later switched to the Trade Representative’s office, serving from 1975 to 1977 as deputy special representative for trade negotiations. For the next eight years, he was president and chief executive of the Chicago Mercantile Exchange, one of the world’s largest futures markets, where he pushed to expand international operations.

Departing Republican National Committee Chairman Clayton Yeutter, left, and his successor, Richard N. Bond, in 1992. (Shayna Brennan/AP)

In 1985, President Ronald Reagan tapped him as U.S. trade representative. Over the next four years, Dr. Yeutter helped pass a nonprotectionist trade bill through Congress, oversaw the completion of the Canada-United States Free Trade Agreement, and negotiated with the Japanese to open their markets to the American computer chip, citrus and beef industries.

Despite his ardent support of free markets, Dr. Yeutter was willing at times to flash the might of American protectionism when other countries — Italy, Japan and South Korea, in particular — were hesitant to engage in fair competition practices.

President George H.W. Bush named Dr. Yeutter to lead the USDA in 1989. Two years later, he was selected RNC chairman. He succeeded Lee Atwater, the hard-edged, blues-loving political consultant who had made his name in negative advertising. Atwater was also dying of brain cancer, and Dr. Yeutter struggled to revive an organization beset with financial difficulties and a splintering party.

Dr. Yeutter criticized many in his party who denounced Bush for violating an earlier pledge for no new taxes. “We have a lot of ideologues who never accomplish anything,” he said at a committee gathering. “It’s great to be pure, but if that means that one doesn’t achieve anything, then there isn’t a whole lot of regard for ideological purity.”

A year later, Dr. Yeutter was brought into the White House as a presidential counselor on domestic policy. Bush lost reelection in 1992, and Dr. Yeutter became a senior adviser at the Hogan Lovells law firm, where he worked until 2015. He also held corporate directorships at ConAgra, the farm equipment manufacturer Caterpillar, the computer chip maker Texas Instruments and British-American Tobacco, among other businesses.

Clayton Keith Yeutter was born in Eustis, Neb., on Dec. 10, 1930. At the University of Nebraska, he received an undergraduate degree (1952), a law degree (1963) and a doctorate (1966). He served in the Air Force in the 1950s and remained in the reserves for 25 years.

He became interested in international trade while directing his alma mater’s agricultural and technical assistance program in Colombia in the late 1960s.

His first wife, Jeanne Vierk, whom he married in 1952, died in 1993. Two years later, he married Cristena Bach. Besides his wife, of Potomac, survivors include four children from his first marriage, Brad Yeutter of Lincoln, Neb.; Gregg Yeutter of Omaha; Kim Bottimore of Vienna, Va., and Van Yeutter of Chevy Chase, Md.; three daughters from his second marriage, Victoria Yeutter, Elena Yeutter and Olivia Yeutter, all of Potomac; nine grandchildren; and a great-granddaughter.