But dozens of abortion clinics around the country are already getting ready to make RU-486 available, now that it has the approval of the Food and Drug Administration.
The FDA ruling Thursday ended a battle that has involved two presidents, several countries and debate for 12 years.
Approval of the drug gives American women a pharmaceutical abortion method already in wide use in France, Britain, China and 10 other countries.
Texas Gov. George W. Bush, the Republican presidential nominee, called the FDA decision "wrong" and said he feared that the availability of RU-486 "will make abortions more and more common."
CBS News Medical Correspondent Dr. Emily Senay reported studies indicate that abortions did not increase after the drug was introduced in Europe.
A Bush campaign spokesman said a president cannot order drugs off the market, but, if elected, Bush will appoint an FDA commissioner who would "make sure the FDA considered the risk and did not take this action as a result of political pressure from the White House."
Vice President Al Gore, Bush's Democratic opponent, supported approval of the abortion pill, saying the decision was "not about politics, but the health and safety of American women and a woman's fundamental right to choose."
Sen. Barbara Boxer, D-Calif., called the FDA ruling one that "finally" respects women's health and their choices.
In Virginia, Judie Brown of the American Life League said the battle against the drug will continue, in opposition to the "destruction of innocent human persons."
RU-486 was developed in France and became available there in 1988. In 1989, Bush's father, President George Bush, ordered the FDA to ba importation of the drug for personal use. In 1993, President Clinton ordered a re-evaluation of the ban and sought ways to provide RU-486 for U.S. researchers after its French manufacturer refused to supply it.
Abortion opponent Rep. Chris Smith, R-N.J., called the abortion pill "baby poison," adding that "RU-486 is not just poison for babies, it is potential poison for the mothers who take it." He said it can cause prolonged bleeding and severe cramps.
The FDA approval already places restrictions on who can prescribe the drug, limiting it to doctors qualified to perform abortions and to diagnose the conditions that would preclude use of RU-486, specifically ectopic pregnancies and pregnancies that have already gone beyond the seventh week.
The pill, known chemically as mifepristone and by the brand name Mifeprex, will be available to doctors within a month.
Mifepristone blocks a hormone vital to sustaining pregnancy and works only during the first seven weeks of pregnancy, when an embryo is about one-fifth of an inch.
Two days afer taking mifepristone, women take a second drug that causes cramping and bleeding as the embryo is expelled.
"For those who choose to have an early termination of their pregnancy, this is a reasonable medical alternative," said FDA Commissioner Jane Henney. She approved mifepristone based on studies that found it 92 percent to 95 percent effective in causing abortion.
Researchers say complications are rare, with serious bleeding occurring in 1 percent of women.
Richard Hausknecht, medical director of Danco Laboratories, marketer of mifepristone, called it "a very, very safe drug."
Yet RU-486 opponent Smith claimed in a statement that a French study shows that out of 950 women who used the drug, 270 required narcotics to control intense pain and seven required blood transfusions.
Mifepristone may "turn the tide against anti-choice intimidation," because doctors not offering surgical abortion can use the pill in private offices instead of protester-targeted clinics, said Planned Parenthood president Gloria Feldt.
"At long last, science trumps anti-abortion politics and medical McCarthyism," said Eleanor Smeal of the Feminist Majority Foundation.
The convenience of RU-486, which requires three doctor's visits but no surgery, is particularly troubling to its opponents.
"It allows the person who might use RU-486, and society at large, to numb their conscience about what a violent act the taking of a life really is," said Monsignor Joseph Schaedel, the vicar general of the Archdiocese of Indianapolis.
A Kaiser Family Foundation survey of 767 physicians found that a third of doctors who don't now provide surgical abortions would consider prescribing RU-486.
In Seattle, a doctor who was involved in the clinical trials is predicting that eventually, about 10 percent of the 1.3 abortions done each year in the United States will be done chemically. Dr. Deborah Oyer of Aurora Medical Services says her clinic used the drug in about 800 abortions in the past six years.
The pill's journey to the United States began in 1995, when French manufacturer Roussel-Uclaf turned over U.S. rights to the drug to the nonprofit Population Council of New York. The council began clinical trials needed for FDA approval and created Danco Laboratories to market mifepristone.
The FDA in 1996 declared mifepristone a safe and effective early abortion method, but delayed full approval because Danco had problems satisfying manufacturing and other final requirements.
President Clinton said the FDA's four-year investigation shows the decision was "purely one of science and medicine." He said the FDA "bent over backward to do a lot of serious inquiries."
©2000, CBS Worldwide Inc., All Rights Reserved. The Associated Press contributed to this report