WASHINGTON — The federal government is grappling with the explosive question of whether to let anyone of any age buy the controversial morning-after pill Plan B directly off drugstore and supermarket shelves without a prescription.

The Food and Drug Administration has until Wednesday to respond to a request from the drug’s manufacturer to make the pill as easy to get as toilet paper and toothpaste, a move pushed by some doctors, health advocates, family planning activists, members of Congress and others to help women prevent unwanted pregnancies.

Opponents contend such a decision would expose girls and women to risks from taking high doses of a potent hormone, interfere with parents’ ability to monitor their children and make it easier for men to prey on vulnerable minors.

The request follows a series of steps in recent years that have gradually made Plan B easier to obtain. If it is approved, the pill would move out from behind pharmacists’ counters, eliminating the requirement that women produce a prescription or prove they are at least 17 to get it without a doctor’s order. Instead, Plan B would be available on store shelves, along with condoms, contraceptive sponges and spermicides.

“We think it’s good news for women’s health and long overdue,” said Kirsten Moore of the Reproductive Health Technologies Project, a Washington-based advocacy group.

Plan B consists of a synthetic form of progesterone, a hormone found in many standard birth-control pills, but Plan B contains it in higher doses. Taken within 72 hours of unprotected sex, the pill has been shown to be 89 percent effective at safely preventing pregnancy.

The drug has long been controversial and was the focus of one of the biggest health disputes during the administration of President George W. Bush. Plan B works primarily by preventing an egg from being fertilized.

Critics focus on the chance that it might prevent a fertilized egg from implanting in the womb, an action they consider equivalent to an abortion.

As a result, it has been the subject of intense debate and conflict. Some doctors refuse to write prescriptions for it; some pharmacists refuse to fill requests; and some hospitals refuse to provide it to patients.

“It’s not a drug that prevents life; it’s a drug that destroys life,” said Jeanne Monahan of the Family Research Council, a conservative advocacy group. “If we define life as beginning at fertilization or conception, then this drug can be an abortifacient.”

The FDA approved Plan B in 1999, but only for women who first obtained a prescription from a doctor. With strong support from women’s health groups and family planning advocates, the drug’s maker asked the FDA in 2003 to ease the rules to allow totally free sale without a prescription so women would not have to scramble to find a doctor to write a prescription and an open pharmacy to fill it.

“If you got into a Wal-Mart and the pharmacy is closed, you’re out of luck,” said Susan Wood of George Washington University, who resigned from the FDA a few years ago to protest the agency’s delays in making Plan B available without a prescription. “By having it on the shelf, more women will become aware of the availability of emergency contraception and won’t have to ask someone in an emergency situation about a very private and personal situation. Hopefully, that will help women when time is of the essence.”