- Having announced two Cabinet choices within a week of winning the White House, President-elect George Bush reportedly has settled on an

unannounced third, tapping New Hampshire Gov. John Sununu to become his chief of staff.

The Washington Post, The New York Times and WCVB-TV in Boston all reported Wednesday the selection of Sununu, retiring this year after three terms in office. He was known to have been in a contest for the key White House job with Bush's current chief of staff, Craig Fuller, who seems sure to fill a top position.The Post, quoting unidentified sources as did the Times and the television station, suggested Sununu, 49, was chosen partly because as an elected leader he outweighs Fuller, 37, in political stature for dealing with Congress.

Sununu is known by many politicians outside his state for the major role he played in helping Bush win this year's New Hampshire primary election after the vice

president was knocked down in the Iowa caucuses by Senate Republican leader Robert Dole of Kansas, who was vying for the party's presidential nod.

Bush would not tip his hand when asked about the chief of staff's position Tuesday, saying only that he wanted to make a decision soon "so that person can start working toward staffing the White House for what will be a very important early beginning there."

The sole announcement Bush was willing to make Tuesday was his decision to retain his friend Nicholas Brady as treasury secretary, sending a message of stabilized economic policy to jittery financial markets around the world.

Brady became the second announced nominee to Bush's Cabinet, following last week's selection of campaign Chairman James Baker, who served President Reagan as treasury secretary and chief of staff, to be the next secretary of state.

The retention of Brady, 58, had been expected. Bush undoubtedly had influence in Reagan's selection of the Wall Street executive to replace Baker when Baker resigned in August to lead Bush's campaign.

Bush's determination to have both men high in his administration sends a clear signal to U.S. allies and to Congress that his White House plans to follow the course Reagan has set.

Indeed, Bush boasted Tuesday that he is fielding "a good team here _ a former secretary of the treasury to be secretary of state (and) a widely respected secretary of treasury to continue. And so you'll see some continuity and some change."

Nevertheless, in the week since Bush's election, world stock and currency exchanges have shuddered with steep declines, apparently fearing the loyal vice president will have difficulty coping with the biggest problems of the Reagan years _ the budget deficit and the nation's trade imbalance.

Bush therefore announced his choice of Brady outside the vice presidential residence after a meeting with West German Chancellor Helmut Kohl at which economic concerns were discussed.

Reaction to the nomination was lukewarm, mainly because Brady "has taken the administration line and nobody really knows what his views are," said Lawrence Chimerine, chief economist with the WEFA Group in Bala Cynwyd, Pa.