Robert P. Griffin, center, with two other Republican senators, George Murphy of California, left, and John J. Williams of Delaware, after the Senate refused to end a 1968 filibuster of the nomination of Abe Fortas as chief justice. (AP)

Robert P. Griffin, a Michigan Republican who served in both houses of Congress, including nearly eight years as the Senate minority whip, and who led a 1968 filibuster that blocked President Lyndon B. Johnson’s nomination of Abe Fortas as chief justice, died April 16 at his home in Traverse City, Mich. He was 91.

His death was confirmed by the Reynolds-Jonkhoff Funeral Home in Traverse City. No details were available.

Mr. Griffin was elected to five terms in the House of Representatives before he was appointed to a vacant Senate seat in 1966 by Michigan’s governor, George Romney (R).

A year earlier, as a member of the House, Mr. Griffin helped engineer the rise to leadership of a fellow Michigander, Gerald R. Ford. With a group of other young Republican congressmen, Mr. Griffin maneuvered behind the scenes to oust Charles A. Halleck (R-Ind.) as minority leader and install Ford in his place.

Mr. Griffin was considered a moderately conservative Republican who seldom made waves. One of the few times he stepped to the front lines came in 1968, when Johnson nominated Fortas, then an associate justice of the Supreme Court, to succeed Earl Warren as chief justice. Fortas and Johnson had been closely associated for decades, and Mr. Griffin said the nomination was “cronyism at its worst.”

Turning against powerful members of his own party, including Senate Minority Leader Everett M. Dirksen (Ill.), Mr. Griffin organized a bipartisan coalition to oppose Fortas’s nomination. He led a four-day filibuster that ended with Fortas withdrawing from consideration.

After Richard M. Nixon was elected president, he nominated Warren E. Burger to be chief justice, and he was confirmed in 1969.

The same year, Mr. Griffin was elected minority whip, his party’s No. 2 position in the Senate. He was considered a rising Republican star, but his loyalty to the party reached its limit during the Watergate scandal, when evidence of White House criminal activity led him to call for Nixon’s resignation.

“It’s not just his enemies who feel that way,” Mr. Griffin said in 1974. “Many of his best friends — and I regard myself as one of those — believe now that this would be the most appropriate course.”

When Nixon stepped down in August 1974, Mr. Griffin’s old friend, Ford, stepped into the Oval Office. But when Ford was defeated by Jimmy Carter in the 1976 presidential election, Mr. Griffin began to lose his hold on power.

He was defeated in a bid for Senate minority leader in 1977 by Howard H. Baker Jr. of Tennessee by a vote of 19 to 18. A year later, Mr. Griffin lost his Senate seat to Democrat Carl Levin, who served until this year.

Robert Paul Griffin was born Nov. 6, 1923, in Detroit. His father was an auto factory foreman.

Mr. Griffin worked on auto assembly lines in his youth and served in the Army in Europe during World War II. He graduated from Central Michigan University in 1947 and from the University of Michigan law school in 1950.

He practiced law in Traverse City before being elected to Congress in 1956. With Philip M. Landrum (D-Ga.), Mr. Griffin sponsored the 1959 Landrum-Griffin Act, which he said was aimed at curtailing labor racketeering. The law imposed restrictions on boycotts, picketing and other activities by labor unions.

In 1973, soon after Vice President Spiro T. Agnew resigned amid accusations of extortion, bribery and tax evasion, several commissions questioned whether vice presidents should be nominated in a different manner or whether the office should be abolished altogether.

Mr. Griffin proposed a constitutional amendment to end the direct election of vice presidents. He suggested that a newly elected president should nominate a vice president, who would be approved by Congress. The ideas went nowhere, and vice presidential candidates are still chosen by presidential nominees.

After his 22-year congressional career, Mr. Griffin returned to Traverse City to practice law. He was elected to an eight-year term on the Michigan Supreme Court in 1986.

Survivors include his wife of 67 years, Marjorie Anderson Griffin of Traverse City, and four children, including Richard A. Griffin, a federal appeals court judge in Cincinnati.

Within weeks of leading the Senate filibuster against the Fortas nomination in 1968, Mr. Griffin said he faced harassment from Johnson-appointed postal officials, who claimed the senator was abusing his privileges of free postage.

“When you stick your neck out and buck the Johnson administration, I guess you have to expect this sort of thing,” Mr. Griffin said at the time. “I’ve advised my relatives and my staff to double-check their income tax returns and fasten their seat belts.”