W. Marvin Watson gestures in the White House after being named postmaster general in 1968. (Henry Burroughs/AP)

W. Marvin Watson Jr., a Texas businessman who became one of President Lyndon B. Johnson’s most loyal confidants, served as his chief of staff in all but name and held the Cabinet position of postmaster general, died Nov. 26 at his home in the Woodlands, Tex., near Houston. He was 93.

The cause was not immediately known, said a son, Lee Watson.

Mr. Watson recalled being drawn to Johnson’s imposing personality from the moment they met in 1948, when the future president was campaigning for a U.S. Senate seat.

It was in Waco, Tex., Mr. Watson recalled, and Johnson made an indelible impression by circling the city by helicopter — a novelty at the time — then tossing out his Stetson hat for the watchful crowd to race after. Mr. Watson, a World War II veteran studying business at Baylor University in Waco, was among the horde.

"He radiated enormous energy, more so than I have observed in any other person before or since," Mr. Watson said in his 2004 memoir, "Chief of Staff," written with another former Johnson aide, Sherwin Markman.

Mr. Watson and his wife in 1968, leaving a Catholic church near the LBJ Ranch with President Lyndon B. Johnson and his daughter Luci. (AP)

The strong connection was mutual. Johnson once called Mr. Watson “the most efficient man I have ever known” and described him as being “as wise as my father, gentle as my mother and loyal to my side as Lady Bird.”

Johnson rose to Senate majority leader in the 1950s, was tapped as John F. Kennedy’s running mate in 1960 and became president after Kennedy’s assassination in November 1963. Meanwhile, Mr. Watson became executive assistant to the president of the Lone Star Steel Co. in Dallas and a behind-the-scenes force in Texas Democratic politics.

Mr. Watson was little known outside Texas when Johnson invited him to join the White House staff in January 1965, months after the president's first chief of staff, Walter Jenkins, resigned after being arrested during a sexual encounter with another man.

Mr. Watson was a Southern Baptist deacon who neither drank nor danced, as Time magazine reported, and “invariably wears a vest and a buttoned-up air of rectitude.” Unlike other Washington operators on the move, he deflected press attention, telling a New York Times reporter that he had “very little power of decision. I try to remember that that’s a fact.”

Despite his modest title of appointments secretary, he became a quiet power broker in his own right, wielding enormous influence over the president’s schedule, daily briefings, and political and judicial appointments. Occupying the office closest to the president’s, Mr. Watson often worked 18-hour days and was Johnson’s liaison to the FBI and to Democratic operatives throughout the country and on Capitol Hill. He was described by the Times as “one of the least known but most important men in Washington.”

A conservative Democrat who never ran for elective office, Mr. Watson was not considered an architect of Johnson’s major legislative policies on civil rights and expansive social programs that came to be called the Great Society. Instead, he seemed content to serve as the president’s gatekeeper, or “Johnson’s “bureaucrat par excellence,” as historian Robert Dallek wrote in his Johnson biography “Flawed Giant.”

After helping during the 1960 campaign, Mr. Watson gained Johnson’s trust by managing the day-to-day details of the 1964 Democratic National Convention. He took credit for blocking the influence of Kennedy loyalists he suspected of plotting to nominate Johnson’s rival, Attorney General Robert F. Kennedy, the assassinated president’s brother, in a convention-floor coup.

No detail escaped Mr. Watson’s discerning eye. While working at the White House, he established strict standards of accountability, not all of which were popular.

“Responding to Johnson’s insistence on a leak-proof administration,” Dallek wrote, Mr. Watson “required that White House operators record all incoming and outgoing calls, including the names of the parties speaking to each other. He insisted that White House chauffeurs report on the destination of any staff member using official transportation.”

Presidential foreign policy adviser McGeorge Bundy protested the watchdog system in a memo to Johnson, and political columnists Rowland Evans and Robert Novak exposed what they called Mr. Watson's "gumshoe tactics" in 1966. The practices were quickly stopped.

Another time, after Johnson casually remarked that he would like to build a wall to keep nosy reporters at bay, Mr. Watson ordered masons to start building a barrier between the Executive Office Building and the White House. Other members of the administration canceled the project.

Mr. Watson was a strong ­behind-the-scenes force who pushed several Kennedy holdovers out of the administration. In his memoir, Mr. Watson said he either fired or helped engineer the dismissals of such top White House advisers as Bundy, Richard Goodwin, Robert E. Kintner and press secretary Bill Moyers.

After three years as de facto chief of staff, Mr. Watson was appointed postmaster general in April 1968, serving in what was then a Cabinet position until Johnson left office the following January.

The teetotaling Mr. Watson tried to shun the Washington party set, but his proximity to the president put him in constant demand. “In this Administration, the next best thing to getting invited to the White House is a summons to socialize with Presidential Assistant Marvin Watson,” Washington Post society columnist Maxine Cheshire wrote in 1968. “You can be almost certain that President and Mrs. Johnson are going to drop by before the evening is over.”

William Marvin Watson Jr. was born in Oakhurst, Tex., on June 6, 1924. His father was an auto dealer.

A talented saxophonist in his youth, Mr. Watson won a music scholarship to Baylor but left to serve in the Marine Corps during World War II. After his discharge, he reentered Baylor on the GI Bill and received a bachelor’s degree and then a master’s degree in economics in 1950.

While in college, he married Marion Baugh. Besides his wife, of the Woodlands, survivors include three children, Lee Watson of Austin, Kimberly Rathmann of Cypress, Tex., and W. Marvin Watson III of the Woodlands; four grandchildren; and three great-grandchildren.

Mr. Watson managed the chamber of commerce in Daingerfield, Tex., before becoming an executive with Lone Star Steel, a company that fired workers during a wildcat strike in 1957.

When he worked in the Johnson White House, Mr. Watson lobbied in favor of certain pro-labor positions, despite being viewed by some as a strikebreaker in his earlier life. “I’m for organized labor,” he said, when pressed by a Times reporter in 1967. “I have never been against organized labor.”

In 1969, Mr. Watson returned to Texas and ran international operations of the Occidental petroleum company. In 1976, he pleaded guilty to a misdemeanor charge of trying to cover up illegal contributions by Occidental’s chairman, Armand Hammer, to Richard M. Nixon’s 1972 reelection campaign.

Mr. Watson later held top positions with technology and pharmaceutical companies and was president of Dallas Baptist University from 1979 to 1987. He served on the boards of corporate, legal and religious organizations.

During his years at the White House, Mr. Watson was known for his mastery of detail. No job was too small or too demeaning.

In a Post review of Mr. Watson’s memoir, Ted Van Dyk, who had been a member of Hubert H. Humphrey’s vice-presidential staff, wrote that his office in the Executive Office Building “overlooked the rear windows of the Oval Office and the meshed-fence area behind it in which LBJ’s beagles, Him and Her, often frolicked.”

One day, either Him or Her — it was impossible to know from a distance — managed to jump over the fence and run onto the White House lawn toward the Ellipse.

“Johnson must have seen the same thing I did,” Van Dyk wrote. “Moments later Watson, wearing a gray suit and vest and black wingtip shoes, broke running from the West Wing basement door in the direction the escaped beagle had taken. Some 10 minutes later he returned, sweating and rumpled, carrying Johnson’s dog in his arms.”