They angered Massachusetts Sen. Edward M. Kennedy by asking him to set up a subcommittee for her to chair to oversee efforts to draft health care legislation, these officials said.
Kennedy, who is battling brain cancer, declined. He has spent much of his career trying to expand health coverage and intends to chair any hearings himself, although he announced Monday that Clinton would lead a working group on insurance coverage.
Clinton's allies also suggested dislodging Sen. Byron Dorgan of North Dakota from his leadership position as head of the Democratic Policy Committee, according to these officials. They described the events on condition of anonymity, saying they were not authorized to discuss them.
Now under consideration for secretary of state in the incoming Obama administration, Clinton may jettison her congressional career altogether, although associates said it was not a certainty she ultimately would decide she wanted a Cabinet post.
If not, she faces a return to the Senate, where she ranks 33rd in seniority among Democrats - 34th if independent Sen. Joe Lieberman of Connecticut is included. She and her allies would have to petition for advancement that her seniority does not confer.
For now, those conversations are on hold, according to Sen. Debbie Stabenow, D-Mich., who has been an advocate for Clinton with fellow Democrats.
If Clinton does not go into the administration, she said: "We expect her to have a significant role. I don't think we've agreed to announce that yet."
Clinton drew an ovation from fellow Democrats on Monday at a postelection closed-door caucus in recognition of the fundraising and other work she had done to help swell the party's majority.
According to one senator present, Senate Majority Leader Harry Reid said that if she didn't move into the Cabinet, there would be new assignments for her in the Senate, a possible hint of a leadership role that reflects her political standing. Reid's spokesman declined to comment.
Clinton's spokesman, Phillip Reines, said the senator told Kennedy and Reid "that she stands ready to help President-elect Obama in any and every way she can to enact comprehensive health care reform, which she has sought for nearly two decades." He called the report about Dorgan "poppycock."
Within the Senate, Clinton's problem is equal parts tradition and timing. She was first elected in 2000, and has not had enough time in office to take over a prominent subcommittee, much less a full committee.
As a member of the Senate Armed Services Committee, she ranks 10th of the 13 Democrats on the panel, not high enough to chair any of the six existing subcommittees.
She is higher up the seniority ladder on the Environment and Public Works Committee, and chaired a subcommittee on Superfund programs in the outgoing Congress.
Her position is eighth in seniority on the panel that Kennedy chairs, the Health, Education, Labor and Pensions Committee. There are only three subcommittees, though, and she is not in line to chair any, barring creation of several more.
Clinton is also seventh in seniority of 11 Democrats on the Aging Committee, but it lacks authority to send legislation to the full Senate.
According to the Senate Historian's Office, the concept of seniority developed in the institution's first half-century. Seniority helped establish committee rosters, replacing time-consuming roll calls in an era when turnover of senators was frequent.
"Looking back to the Senate of the 19th century, when the average life expectancy of an American was slightly above the age of 40, few senators would have believed it possible to serve 30, let alone 40 years," the office's Web site says.
The first senator to achieve 30 years in office was Missouri's Thomas Hart Benton in 1851. It was another 40 years before anyone matched his longevity, according to the Web site.
Now, eight incumbent senators have 30 years in office, of whom three have been in the Senate for four decades or longer.
Inevitably, they hold the most powerful positions, a series of committee and subcommittee chairmanships if they are in the majority party, or influential assignments if in the minority.
With few exceptions, once gained, a chairmanship is given up only in pursuit of a better one, meaning turnover is relatively rare.
And Clinton's not the only one affected.
After a long tenure as chairman of the Senate Appropriations Committee, West Virginia Sen. Robert Byrd, 90, announced recently he would relinquish the gavel, setting off chairmanship changes in a several major committees.
After 37 years on the Appropriations Committee, many spent as second-ranking Democrat, Sen. Daniel Inouye of Hawaii will succeed Byrd. Inouye is 84.