John Osborne, 74, a son of the Deep South a former foreign correspondent who was widely respected for his coverage of the White House for The New Republic magazine from President Nixon to President Reagan, died Saturday at Sibley Memorial Hospital. He had cancer and emphysema.

Despite his illness, Mr. Osborne remained active until his death. His last article for The New Republic appeared in the April 11 issue and discussed the events surrounding the assassination attempt against Reagan. It concluded with a sentence that was characteristic of his careful and even-handed work for a magazine of opinion.

In connection with the controversial events that occurrred while Reagan was still in surgery and during which Secretary of State Alexander M. Haig asserted that he was "in control," Mr. Osborne concluded: "There is a problem with Haig. He is immensely capable and the country will be the loser if he does himself out of a job."

From 1970 to 1975, Mr. Osborne annually published volumes called "The Nixon Watch." In 1977, he published "The White House Watch: The Ford Years." All of these books were compilations of his columns for The New Republic, of which he was a senior editor.

A hallmark of Mr. Osborne's working style was the attention he paid to official documents that sometimess are overlooked by journalists. That, and talking to people. He often took controversial positions -- he supported President Ford's unconditional pardon of Nixon despite a nationwide outcry against that action, particularly, perhaps, among the liberal readers of his magazine -- and he was ready to admit his own mistakes (his books are larded with footnotes in which he admits the errors he committed).

In an interview with The Washington Post in 1977, he explained, in a voice that retained the accents of his native Mississippi, how he operated:

"My stuff is based on legwork. I get to know and see as many people as possible. I read transcripts of White House business. I get on the telephone. Sometimes I go to lunch with them, but that's mainly to cultivate acquaintances."

As far as Mr. Osborne was concerned, he did his most important work when other reporters were not around. He attended formal media events, such as press conferences, but rarely asked a question. In an article in The New Republic in 1972 at the beginning of Wateregate, the scandal that eventually brought Nixon down, he explained why.

"Readers say in letters that they are variously shocked, angered, horrified, insulted, devastated, dismayed and appalled by my confession in The New Republic . . . that I stood within 10 feet of Presidnet Nixon at a press conference in California and didn't even try to ask him a simple and obvious question about the bugging of the Democratic Party's Washington headquarters . . ." he wrote. "Well, hell's fire, I wasn't afraid to ask the question . . . I didn't try very hard for two reasons. They are that I prefer to do my serious questioning in private, with the various Nixon assistants who grant me audience now and then, and that I hold public press conferences in very low esteem."

He added that his purpose was not to "drive Mr. Nixon up the wall that my complaining readers want to see him pasted to. My purpose is to convey as clear a portrayal of him and his policies as I am capable of conveying. If the portrayal drives him up the wall, which I doubt, so be it."

Hendrik Hertzberg, editor of the New Republic, called Mr. Osborne a "scrupulously fair and painstaking reporter, a fine writer and an admirable, generous man" whose death is "a very great loss" to the magazine and to public understanding of the presidency and its workings.

Mr. Osborne, who was born in Corinth, Miss., attended Southwestern University and the University of Colorado. He began his career in the news business with the Memphis Commerical Appeal and the Associated Press. From 1933 to 1935, he was a public information officer with the Tennessee Valley Authority and ten with the National Recovery Administration. From 1936 to 1938, he was a correspondent for Newsweek magazine. In 1938, Mr. Osborne joined Time magazine and remained with it as a reporter and editor until 1961.

During World War II, he was a foreign correspondent. He covered the "blitz" in London and other aspects of the fighting in Europe. After the war, he opened the Time bureau in Rome. His next foreign assignment was in Toyko, from which he helped cover the Korean conflict. He was back in Europe to cover the Soviet invasion of Hungary in 1956. He then was transferred to Washington and lived in the city for the rest of his life.

Mr. Osborne was a free-lance writer from 1961, when he resigned from Time, until he joined the staff of The New Republic in 1968.

In addition to his White House books, he published "Britain: A Country of Character" (1961) and "The Old South" (1965).

He was a member of the Federal City and Cosmos clubs.

Survivors include his wife, the former Gertrude McCullough, whom he married in 1942, of Washington, and one son, John Franklin Osborne III of Chicago.