WASHINGTON — Federal health officials thought a surprise announcement about the morning-after pill would smooth the Senate confirmation of Dr. Andrew von Eschenbach as commissioner of the Food and Drug Administration.

Instead lawmakers questioned both the timing and sincerity of the news that the FDA would again consider allowing the emergency contraceptive pills to be sold to adult women without a prescription.

The Monday announcement came on the eve of a Senate committee hearing on von Eschenbach's nomination. The FDA hoped it would free up von Eschenbach to discuss his plans and vision for the agency.

Instead, two of the Senators on the panel renewed their vow to block his nomination until the FDA made a final decision on whether to allow Barr Pharmaceuticals to sell Plan B over the counter to women 18 and older. Minors would still need a doctor's prescription.

Sens. Patty Murray, D-Wash., and Hillary Rodham Clinton, D-N.Y., had placed a similar hold on von Eschenbach's predecessor, Lester Crawford.

They removed that hold more than a year ago in exchange for a pledge that the FDA would act on Barr's application. Crawford won Senate confirmation but then put off a decision on Plan B, earning the enmity of the two lawmakers.

"Fool me once. We are not going to go there again. We will hold this nomination until we have a decision on Plan B," said Murray, calling the timing of Monday's announcement "highly suspect behavior."

Crawford resigned abruptly in September 2005 only two months after the Senate confirmed him to run the agency. Von Eschenbach has been acting FDA commissioner since then. In March, President Bush nominated the urology surgeon to lead the regulatory agency on a full-time basis.

The morning-after pill is a high dose of the most common ingredient in regular birth control pills. When taken within 72 hours of unprotected sex, the two-pill series can lower the risk of pregnancy by up to 89 percent.

Since 2003, the Women's Capital Corp. and then Barr have sought to loosen the prescription-only restriction on Plan B.

Contraceptive advocates and doctors groups say easier access to Plan B could halve the nation's 3 million annual unintended pregnancies. Opponents say wider access to the pill could promote promiscuity.

The FDA's own scientists say the pills are safe, and in December 2003 a panel of independent advisers overwhelmingly backed nonprescription sales for all ages.

The FDA rejected that recommendation, citing concern that young teens could use the pills without a doctor's supervision. Barr initially had sought approval for over-the-counter sales without age restrictions, but later amended its application to ask for permission to sell to females 16 and older.