President Carter named White House aide Jack Watson as his interim chief of staff yesterday to replace Hamilton Jordan, who is taking a leave of absence to direct the president's reelection campaign strategy.

White House press secretary Jody Powell said, in announcing the change, that Watson "will have the same range of responsibility and authority" as Jordan had, including active involvement in foreign policy. He added that Watson had the president's "full confidence."

Watson, 42, has served as presidential assistant for intergovernmental relations and secretary to the Cabinet. Powell made clear that Watson would serve as chief of staff only during Jordan's absence during the campaign.

In making the shifts, Carter is putting his political house in order for the fall campaign season.

Jordan's move to the campaign committee will mean that he will now spend full time doing what he had previously done part time -- planning and implementing Carter's reelection strategy.

At the Carter-Mondale campaign committee, Jordan will have the title of deputy chairman. Robert S. Strauss will remain as campaign chairman, and Tim Kraft will serve as champaign, manager. But Jordan clearly will be first among equals, by virtue of the fact that he is personally the closet to the president and has mapped the strategy for Carter 1976 and 1980 campaigns.

The president was concerned, according to his senior advisers, that Jordan would be unable to devote full time to campaign strategy while remaining as chief of staff. "Hamilton's attention would not be completely on the campaign," saie one top adviser. "In the White House, the problems just seemed to come to his door -- from everything right down to White House mess [dining room] privileges."

The appointment of Watson also has its political pluses in this election year. As Carter's liaison to state and local government, Watson has been in constant contact with the nation's governors and mayors, and he is generally well regarded by them.

While Watson will assume the daily duties of the chief of staff, presidential advisers said they expect that Jordan will still remain influential in major White House decision-making. "Watson will be there, but Hamilton will still be around," said one senior adviser.

In the transition days before Carter's inauguration, Watson and Jordan were battling for the position of top influence in the Carter White House. Watson, asked by Carter to prepare a plan for the structure of the White House staff, designed a small role for Jordan and a large role for himself. But in the intra-staff battle that followed, Jordan won.

Powell said there was "some ambivalence here about Hamilton leaving the White House. But in a tough general election campaign -- which we expect it to be -- it was felt we'd all be better off if Hamilton could devote full time to the campaign."

As a white house aide, Jordan has been restricted by law from working on the campaign except outside his regular work schedule, but Powell said that by Wednesday of each week, Jordan has alreday put in 43 hours, implying that he then was able to devote considerable time to the campaign.

However, the election apparently requires even more of Jordan's attention."

"A general election campaign is 40 days and 40 nights like the great flood," Powell said.

The idea of having Jordan move out of the White House and to the campaign committee for the general election has been under discussion for some time.

On May 14, at a meeting in the Hay Adams Hotel of about 20 officials from the Carter White House and the Carter campaign committee, campaign manager Kraft is said to have asked Jordan if he had considered making the move. Jordan said that he had, but that he had reached no decision.

Some of those present at the time believed that Kraft, who is a close friend of Jordan, would not have brought the matter up at that semipublic campaign session if they had not already discussed it privately and if they were not trying to float a sort of in-house trial balloon.

Strauss has said that he urged Carter to shift Jordan to the committee on a couple of occasions this month.

On Sunday night, Strauss discussed the proposal once more, according to informed sources at a meeting in the White House attended by Rosalynn Carter, Vice President Mondale, Jordan, media adviser Gerald rafshoon and Powell.

The President listened but gave no final decision.

At that meeting, the sources said, a number of other political topics were also discussed. Among them was the matter of debating independent candidate John B. Anderson. Carter is said by one source to have declared flatly at that meeting that he was willing to debate Anderson and he was going to say so.

The White House had flatly ruled out a debate involving Anderson. On Tuesday, Carter told reporters in an interview aboard Air Force One, while flying back to Washington from Seattle, that in addition to debating Reagan, "it may be advisable" for him to debate other presidential candidates, including Anderson.

Watson wil be replaced as assistant to the president for intergovernmental affairs and secretary to the Cabinet by his deputy, Eugene Eidenberg. As chief of staff, Watson will continue to be paid at his present top-level rate of $59,080 a year. Eidenberg will be raised to that level from his current salary of $51,168.

Jordan will be on leave without pay from the White House. A campaign aide said his new salary had not yet been discussed.