Brooks, who died Tuesday at age 89, was in the Dallas motorcade on Nov. 22, 1963, when President John F. Kennedy was assassinated. Hours later he stood behind the grief-stricken widow in the cabin of Air Force One as Johnson took the oath of office.
Brooks died at Baptist Hospital of Beaumont after a sudden illness surrounded by his family, the Jefferson County Sheriff's Department said. Brooks would have turned 90 on Dec. 18.
Brooks was among the last links to an era when Democrats dominated Texas politics and was the last of "Mr. Sam's Boys," protégés of fellow Texan and legendary 21-year Democratic House Speaker Sam Rayburn in the state's congressional delegation.
"I'm just like old man Rayburn," Brooks, from Beaumont, once said. "Just a Democrat, no prefix or suffix."
He also was a contemporary and supporter of Johnson, who was U.S. Senate majority leader in the 1950s.
Vice President Joe Biden, who served as chairman of the Senate Judiciary Committee while Brooks headed its counterpart in the House, said Brooks "was a Texan through and through -
"We lost a great American, a great Texan, and a great Democrat," Texas Democratic Party Chairman Gilberto Hinojosa said Wednesday. "During his long and distinguished service he was a champion for working families and equal rights.
Brooks' secretary Dianna Coffey said a birthday party was planned for him next Friday, but he suddenly became ill Tuesday morning.
Coffey, who said she insisted Brooks stop coming to his office about five years ago, worked out of his home and spent weekends at his farm in Jasper, about 60 miles to the north.
When people would ask Brooks what he did in retirement, she said the plain-spoken Texan would reply: "Pretty much what I damn well please."
Brooks, first elected to the House in his far Southeast Texas district in 1952, was returned to office 20 more times. He was on the verge of becoming the dean of the U.S. House when he was ousted in the Republican revolution of 1994.
Rayburn, whose 48 years rivaled Brooks' House tenure, put Brooks on the House Government Operations Committee, a panel Brooks eventually would chair. Brooks gained notoriety as a curmudgeon-like scourge of bureaucrats he grilled for wasting taxpayers' money, peering at witnesses over his glasses as he chewed on a cigar.
"I never thought being a congressman was supposed to be an easy job, and it doesn't bother me a bit to be in a good fight," Brooks once said.
A Brooks-authored law required full and open competition to be the standard for awarding federal contracts. The 1965 Brooks Act set policy for the government's computer acquisition program, requiring competitive bidding and central management. His Inspector General Act established independent Offices of Inspector General in major agencies to prevent fraud and waste.
Other Brooks bills reduced federal paperwork, provided a uniform system of federal procurement, eliminated overlapping audit requirements and established the Department of Education.
"He literally has saved American taxpayers billions of dollars through his actions in improving government efficiency and eliminating waste," former Texas Gov. Dolph Briscoe, a longtime friend who died in 2010, said two years earlier when Brooks donated his congressional papers, photos, correspondence and other items to the Center for American History at the University of Texas.
Brooks also served on the House Judiciary Committee, where he strongly supported Nixon's impeachment and drafted the articles of impeachment the judiciary panel adopted. Nixon, who resigned Aug. 8, 1974, referred to Brooks as "the executioner."
Jack Bascom Brooks was born Dec. 18, 1922, in Crowley, La., and moved to Texas at age 5. While in public schools, he worked as a carhop, grocery clerk, magazine salesman and a reporter for the Beaumont Enterprise. He attended Lamar University in Beaumont, then a two-year school, and earned a degree in journalism from the University of Texas. He served with the Marines in the Pacific in World War II and retired as a colonel from the Marine Corps Reserves in 1972. He received a law degree from the University of Texas and was a two-term Texas state legislator when he was elected to the U.S. House at age 29.
He supported civil rights bills, refused to sign the segregationist "Southern manifesto" in 1956 and helped write the historic Civil Rights Act of 1964 that banned racial segregation.
His congressional longevity was an issue for him and other long-serving Democrats who were swept from office in 1994. Brooks also had alienated gun owners for supporting a ban on assault weapons and abortion opponents for his support of abortion rights.
Brooks married Charlotte Collins in 1960 and the couple had three children, Jeb Brooks, Kate Brooks Carroll and Kim Brooks, and two grandchildren, Matthew Carroll and Brooke Carroll.
Associated Press writer Christopher Sherman in McAllen contributed to this report.