Unconfirmed rumors began seeping out of Capitol Hill late today that Maryland Sen. Barbara A. Mikulski is under consideration for the suddenly vacant position of Secretary of Health and Human Services.

A spokeswoman for Mikulski did not immediately return email and cellphone messages, which only added to the mystery. The White House had no comment, but it does not typically respond to reports about prospective appointments unless they are about to be made public.

Former Sen. Tom Daschle withdrew abruptly as President Barack Obama's nominee for the position, which oversees an enormous swath of the federal establishment, including Medicare, the largest government-run health program.

Mikulski, who is up for re-election in 2010, has already begun raising funds for a re-election bid, though she has not formally announced her intention to run. She was first elected to the Senate in 1986.

She would turn 80 in the final year of her next term, if she were to be re-elected, which she almost certainly would if she ran. Mikulski regularly ranks as the most popular elected official in the state and no serious Republican candidate is likely to take her on.

Her image as a feisty spokeswoman for working-class voters could be an asset at HHS, particularly as the Obama administration attempts to sell its health care overhaul plan to the nation. She is also well-versed in the details of Medicare and of Social Security, an independent agency that works closely with HHS.

The Centers for Medicare and Medicaid Services, which administer those programs and the State Children's Health Insurance Program, are headquartered in Baltimore. So is the central office of the Social Security Administration.

Mikulski could also be in line to become the chairman of a major committee for the first time in her Senate career. Massachusetts Sen. Edward M. Kennedy, chairman of the Senate Health, Education, Labor and Pensions committee, has been treated for a brain tumor and Mikulski is the most senior member of the panel who does not currently chair a major committee.

She is also a high-ranking member of the powerful Senate Appropriations Committee.

Others who have been mentioned as possible choices for the HHS job include Kansas Gov. Kathleen Sebelius, Ohio Gov. Ted Strickland and former Democratic National Chairman Howard Dean, a former governor and a physician by training.