Tom Johnson, the former publisher of the Los Angeles Times and a onetime White House press aide, is expected to be named president of Cable News Network, sources said yesterday.

The announcement of Johnson's appointment to the top position at the international cable television network could come as early as today, according to people inside Turner Broadcasting System, CNN's parent company. Johnson, 48, yesterday was traveling to Seattle, where TBS Chairman Ted Turner is staging the Goodwill Games sports festival, and was unavailable for comment.

Johnson, who apparently lost a bid last year to become chief executive of the Times Mirror Co., the parent of the Los Angeles Times, is expected to replace Burt Reinhardt, 70, as the head of Atlanta-based CNN. Reinhardt's plans were unclear yesterday.

Although rumors of Reinhardt's departure have been circulating for about a year, Johnson was considered a surprise choice to some at CNN. Insiders had expected Turner to select Reinhardt's successor from inside the network, with the leading candidates believed to have been Executive Vice Presidents Ed Turner (no relation) and Paul Amos, and Lou Dobbs, vice president of business news and a CNN anchor.

CNN officials declined to comment.

CNN was dismissed as a business and news-gathering venture by much of the media industry when the network was started by Ted Turner 10 years ago. But it has become both a runaway commercial success and arguably the world's most important electronic news-gathering organization, with viewers in 90 countries, including a potential audience of 55 million households in the United States.

As president of CNN, Johnson will oversee the network's news operations and advertising sales, reporting to Turner. It was not known if Johnson would also be given a seat on the TBS board.

Johnson, whose full name is Wyatt Thomas Johnson Jr., currently is vice chairman of the Times Mirror Co. and chairman of that company's flagship newspaper, the Los Angeles Times. He had been publisher of the Times for nine years -- the first person outside the dynastic Chandler family to hold the job -- until being replaced by Times Mirror President David Laventhol last August.

Johnson's move to an administrative job within Times Mirror was generally viewed as confirmation that Times Mirror's board had anointed Laventhol as heir apparent to Times Mirror Chairman and chief executive Robert F. Erburu, passing over Johnson. Indeed, Johnson is said by associates to have considered several job offers during the past year before deciding on the CNN post.

"I think that after you've been the publisher of the Los Angeles Times, in effect the quarterback of the game, it is considerably less fun and less challenging to have a job in the front office, where you're not really running something," said David Shaw, the Times' media critic and a friend of Johnson's.

As publisher of the Times, Johnson oversaw a newspaper that was one of the most prosperous and journalistically admired in the country. But although the Times dominates the sprawling Southern California area generally, under Johnson it had a tough time battling feisty suburban competitors in Orange County and the San Fernando Valley.

Johnson, who holds an MBA from Harvard, was a reporter for the daily newspaper in his hometown of Macon, Ga., for seven years before becoming a White House fellow in 1965. He was an assistant press secretary under future television host Bill Moyers in the Johnson White House in 1966 and 1967, and was later an executive assistant to LBJ.

In the mid-1970s, he became editor and publisher of the Dallas Times Herald, then a Times Mirror paper, before becoming president of the Los Angeles Times in 1977.

Johnson's last experience running a broadcast operation was from 1970 to 1973, when he was executive vice president of a combined television and radio station in Austin, Tex.