Cheryl D. Mills, the young White House lawyer who vaulted to fame when she represented President Clinton on the floor of the Senate in last winter's impeachment trial, has turned down Clinton's offer to be White House counsel.

If Mills had accepted the promotion, which Clinton suggested earlier this summer, it would have had historic overtones because she would have been both the first woman and the first African American to hold the pivotal post. But White House officials said Mills, after weeks of consideration, on Friday gave Clinton and Chief of Staff John D. Podesta her answer: No thanks.

Mills, 34, who has been at the Clinton White House since its opening days in 1993 and is known internally as a fierce Clinton loyalist, has agreed to serve for several weeks as acting White House counsel while the president searches for another candidate to replace Charles F. C. Ruff, who had held the job since 1997 and served his last day Friday.

Despite Mills's rebuff, Clinton can boast of one precedent-setting White House appointment, effective today. Clinton offered his top speechwriting post to Terry Edmonds, who is the first African American to hold that job at the White House.

Edmonds, who held lower-ranking speechwriting posts for Clinton earlier in the administration before joining the Social Security Administration, has helped draft many of the president's major speeches on race relations. These include an October 1995 address in Texas on the day the "Million Man March" was taking place in Washington and a June 1997 speech in San Diego inaugurating an attempted year-long national "conversation" on race relations. Clinton's effort to stir constructive debate by appointing a commission to study race relations has been widely criticized as ineffectual, but Edmonds, 49 and a graduate of Morgan State University, is helping Clinton draft a book reporting his own conclusions.

Podesta, in a weekend interview, said Edmonds has "impressed everybody with both the quality of his writing and his ability to capture the president's voice."

Edmonds won the job, sources said, over two other internal candidates. He began the administration writing speeches for Health and Human Services Secretary Donna E. Shalala; in the 1980s, he worked briefly for then-Rep. Kweisi Mfume (D-Md.), now head of the NAACP.

More than the Edmonds promotion, it was Mills's refusal that was stirring talk in White House circles this weekend. While some were surprised that a young and ambitious lawyer would turn down a coveted Washington job, the decision was in many ways in keeping with the enigmatic reputation Mills has fashioned at the White House.

Mills, educated at the University of Virginia and Stanford Law School, is widely respected at the White House for a sharp intellect and disciplined work style, as well as her civic-mindedness (she complements her long work hours by volunteering at a mentoring program, D.C. Works, for troubled youth).

Yet she is also a deeply divisive figure within Clinton circles. In the perennial internal debate about how forthcoming the Clinton White House should be in publicly responding to various legal and ethical controversies, Mills, in her current post as deputy counsel, usually has been an advocate of official secrecy -- not public disclosure.

Despite her central behind-the-scenes role over several years, Mills cut virtually no public profile until last January, when she joined Ruff and other members of the legal team to argue in the well of the Senate. Her poised performance caused a brief sensation, but as soon as the impeachment drama was over, Mills seemed eager to resume her low profile, a choice reaffirmed by her decision not to seek the counsel's job.

Mills did not return pager messages this weekend seeking comment on her choice. White House associates said she has an appealing private-sector job offer in New York, not with a law firm. Some colleagues hope, however, that she will reconsider and decide to make her acting position permanent.

Podesta said he was disappointed by Mills's decision but can understand it, particularly since she has worked punishing hours for nearly seven years already. "I think she concluded after going back and forth that she would resist our entreaties," he said. "She wants a life, I think. . . . The normal pressures of ladder-climbing Washington don't affect her much."

White House officials said there are a handful of candidates from outside the White House under consideration as a permanent replacement for Ruff.