WASHINGTON (AP) _ ''Stay Tuned'' is the standard answer from the Bush camp these days when asked about the timing of the next appointments to administration jobs.

Sheila Tate, spokeswoman for President-elect George Bush's transition office, most recently gave the response when reporters asked her when the new defense secretary might be named. ''And don't be too far from the phone,'' she added.

Bush, who insists that only he knows when appointments will come, made a surprise announcement Monday, picking White House spokesman Marlin Fitzwater to say on in the post. Tate had already taken herself out of the running.

Another woman dropped out of the race Monday, Labor Secretary Ann McLaughlin. ''I have indicated to my own staff that I plan to return to the private sector and find other ways to help,'' McLaughlin said in Norfolk, Va.

Bush already had indicated that he would not keep any more incumbent Cabinet members in their jobs. Already staying are Treasury Secretary Nicholas Brady, Attorney General Dick Thornburgh and Education Secretary Lauro Cavazos.

For over a week, reports have circulated that former Sen. John Tower of Texas is the front-runner for the Pentagon job. A source close to the Bush transition office said a decision on Tower could come today or Wednesday.

The source, who spoke on condition he not be named, said the president- elect likes Tower and thinks he would do a good job at the Pentagon. But some Bush advisers have raised objections, partly because they do not have a high regard for a number of people who have worked for Tower and might have an inside track for top Pentagon jobs should he be named.

Another Texan, Robert Mosbacher, is supposed to have a lock on the job of commerce secretary. Mosbacher, an oilman from Houston, is a close friend of Bush's.

Here is some other new speculation about key jobs:

- Two Missourians, Rep. E. Thomas Coleman of Missouri and Peter C. Myers, the No. 2 person at the Agriculture Department, have emerged as competitors for the top position at the department. Coleman is the ranking Republican on the House Agriculture Committee; Myers, a hog and grain farmer, has been head of the Soil Conservation Service.

- Sources said Monday that Robert Helander, a former vice president of the Pan American Society of New York, was being mentioned as a possible successor to Elliott Abrams as assistant secretary of state for inter-American affairs. Abrams was an outspoken supporter of the Nicaraguan Contra guerrillas.

- Sources also said David Gergen, the editor-at-large of U.S. News & World Report and a former White House communications chief, may be a candidate to be ambassador to the Organization of American States.

- Bush may also make a decision soon on the CIA director. Some think he might keep current director William Webster in the post for a limited length of time.