IT USED TO BE SAID of Lyndon Johnson that whenever he felt the urge to sacrifice a little political capital for the sake of principle, he would lie down until it passed. A generation of Texas Democratic leaders learned that policy at the knee of House Speaker Sam Rayburn, a Texan whose favorite motto was "to get along, go along." That attitude helped make Rayburn the longest-tenured Speaker the House has ever had--he held the job for a total of 17 years--and probably the most influential politician in Texas history. Fourteen years after his death, Texas politics is still dominated by Rayburn proteges like John Connally, Lloyd Bentsen and others of the same ilk--practical, adaptable men who relish the exercise of power for its own sake and maintain a highly skeptical regard for principles and ideologies.

One could make a persuasive case that such men, if not wholly admirable, are an indispensable part of the American political system and should not be despised merely because they fail to transcend its limitations. But, as Richard Nixon used to say, that would be the easy way. Instead, whether out of gullibility or perversity, Steinberg has chosen to portray Rayburn as a statesman of principle, integrity and elevated vision--a poor country boy who, through hard work and trust in the Lord, grew up to be "by far the greatest" Speaker in American history, and a hell of a cracker-barrel philosopher to boot.

That kind of approach works fine for presidential campaign biographies and The Lou Gehrig Story, but it's pretty thin stuff for serious historical scholarship. The result is a tedious, one-dimensional narrative that reveals little about Rayburn the Speaker or Rayburn the man. Steinberg generally hovers at the level of cliche, as in his description of young Rayburn's reaction to a speech by Texas Congressman Joe Bailey: "With a prophecy born of youthful excitement, he predicted that one day he would also become a congressman like Bailey."

STEINBERG'S UNDISGUISED liberal Democratic bias and his simplistic hyperbole also mar his account. He refers to President Coolidge's second term as "four more years of what became known as the 'Roaring Twenties,' an era of gangsterism, wholesale violation of the Eighteenth Amendment, and an insane speculation in stocks and real estate." Given a choice between repeating the most trite, superficial accounts of history and attempting a more sophisticated version, Steinberg invariably prefers the former.

Steinberg tries without much success to paint Rayburn as a courageous defender of liberal principles. For example, he notes approvingly Rayburn's agreement with Harry Truman's remark that "Nixon probably never read the Constitution, and if by chance he had he did not understand it." At the same time, he minimizes Rayburn's support of Truman's unconstitutional seizure of the nation's steel mills during the Korean War and of Wilson's Sedition Act, under which hundreds of citizens were jailed for denouncing the United States' role in World War I.

Steinberg also depicts Rayburn as an early friend of blacks, despite his rejection of Truman's 1948 civil rights package, which included the elimination of some Jim Crow laws, the abolition of the poll tax and a federal anti-lynching law. Steinberg's explanation: "Rayburn knew that his friend's program now made humanitarian sense but absolutely no political sense in an election year." He doesn't even try to explain away such positions as Rayburn's belief during World War I that the U.S. should "close the immigration gates and open up the emigration gates to deport a lot of European trash we have accumulated."

AS IF THIS weren't enough, Steinberg includes an appendix consisting of particularly cogent remarks by Rayburn, which he calls "Rayburnisms." It includes profundities like "The size of a man has nothing to do with his height" and "Any jackass can kick a barn down, but it takes a carpenter to build it."

In his obsession with glorifying Rayburn, Steinberg ignores not only his faults but also important questions about him. He offers no convincing explanation for Rayburn's support of the New Deal, his torpedoing of John Kennedy's attempt to gain the Democratic vice presidential nomination in 1956 or the failure of his only marriage after three months. A biographer with a critical eye could probably make Rayburn reasonably interesting, but Steinberg is unable to step back far enough from his subject to handle his account in a balanced and scholarly manner. Steinberg, in short, lacks the ability that Lyndon Johnson described so succinctly after hearing a Nixon speech: "Well, I may not know much, but I know the difference between chicken salad and chicken shit."