Mark McGwire's little home run pill is about to be pulled off the shelves.

That's the intent of a new bill sponsored by influential senators on both sides of the aisle, who introduced legislation late Thursday night that would prevent the over-the-counter sale of androstenedione and its muscle-building chemical cousins. The bill would also ban THG, the substance at the center of a growing scandal involving several elite athletes.

"These substances, called steroid precursors or pro-steroids, are one step removed from the substances [regulated] in the law," Sen. Joseph Biden, D-Delaware, said on the Senate floor. "When ingested, they metabolize into testosterone or other illicit steroids. These are products which the United States Anti-Doping Agency, the group in charge of testing Olympic athletes for performance enhancing drugs, has called the 'functional equivalent of steroids.' "

Biden was the driving force behind the effort in 1990 that led to anabolic steroids being made controlled substances. The new bill, the Anabolic Steroid Control Act of 2003, serves as acknowledgement that there were flaws in that original legislation, which discouraged doctors from prescribing steroids to athletes but stimulated the black market and encouraged scientists to devise powerful substances that were technically legal.

THG, a designer steroid undetectable by drug tests and kept secret until recently, is one of those substances. Although not sold in health stores -- like andro is -- the substance has the potential to become available over the counter once it becomes better known.

The bill is co-sponsored by Orrin Hatch, R-Utah, whose support is considered critical to the bill's passage, Senate staffers familiar with the legislation told ESPN.com. Hatch was a leader in a successful 1994 effort to deregulate the nutritional supplement industry, which has spawned many of the ethically-suspect products used by athletes in recent years. Over the years, he has been perceived as a protector of the industry as calls have increased for greater government oversight of products such as andro.

Hatch has said the fault lies not with the legislation but with the Food and Drug Administration, which he believes should be more aggressive in determining that such substances fall outside the scope of existing law.

"I have been extremely frustrated by the lack of regulatory action on these performance-enhancing products," Hatch said in a statement. "For years, I have asked the FDA to explain how these dangerous products could be marketed freely to our teens, but I've never received an adequate response. Our hand has been forced -- we must act to ensure no more young athletes are placed at risk."

The bill would not ban many of the more popular substances, such as ephedra and creatine, used by athletes to enhance performance.

The Senate bill gives renewed vitality to a similar bill introduced in January in the House of Representatives by Rep. John Sweeney, R-N.Y., and Tom Osborne, R-Neb., the former football coach at the University of Nebraska. Sweeney said Friday he became aware of the steroid precursor issue in the wake of McGwire's andro revelations and his teenage son's reaction to it.

"My son wanted to take andro because Mark McGwire did," he said.

Andro, which is banned in the NFL and other sports but not in baseball, was used by McGwire during the 1998 season when he hit 70 home runs, breaking the single-season record owned by Roger Maris. Andro sales quadrupled after his admission, with teenagers making up many of those consumers.

At the time, McGwire dismissed public concerns about his use of andro, and discounted comparisons to anabolic steroids, because the pills were available over the counter.

McGwire could not be reached Friday for comment. His former agent, Robert Cohen, said he would relay an interview request from ESPN.com, but doubted the retired baseball player would respond.

"He'll be running away from that one," Cohen said. "He isn't going to want to talk about it."

Major League Baseball was one of the 34 organizations listed as supporting the bill, which is endorsed by a wide range of medical, athletic and drug policy groups. Several groups are from the nutritional supplement industry.

"Our major sports organizations are banning pro-steroids because they know what our kids don't -- that these substances carry serious risks," Hatch said. "The federal government must take action. This bill will give our regulatory agencies the precise tools necessary to ensure that consumers have the choice of safe, health-enhancing products without these potentially dangerous side-effects."

Andro increases both testosterone and estrogen levels in the body. Biden cited a study published in the Journal of the American Medical Association concluding that "orally administered androstenedione increases testosterone and estrogen levels in healthy men, particularly at higher doses." The study also notes that long-term administration could be hazardous, particularly in women and children.

"To be honest, I would be less concerned about what professional athletes are doing to their bodies if their actions did not have such a profound effect on kids," Biden said.

If the bill passes, people who want to use andro or its chemical cousins would have to get a prescription from a doctor. Biden said the bill would also make it easier for the Drug Enforcement Administration to add new substances to the controlled substances list.

Government agencies have been largely impotent in dealing with the steroids issue. As ESPN.com previously showed in an investigative report on the steroids trade, even those trafficking in the hard stuff -- anabolic steroids -- face few consequences. Stopping the flow of steroids from Mexico is a low priority for border guards, and steroids dealers in the U.S. rarely get any prison time.

Currently, the maximum sentence for offenses involving anabolic steroids is only 33 to 41 months for first-time offenders, and to receive the maximum sentence an offender would have to be caught with 300,000 doses.

The Biden-Hatch bill directs the U.S. Sentencing Commission to review the federal sentencing guidelines for crimes involving anabolic steroids, and consider raising them.

Biden and Hatch are scheduled to speak at a hearing Tuesday that has been called by Sen. John McCain, R-Arizona, who has introduced a separate bill that calls for more research into performance-enhancing drugs used by athletes.

The supplement industry has come under increasing scrutiny in recent years, largely because of high-profile cases involving athletes. In addition to the Mark McGwire andro controversy, there is the current Balco investigation that has resulted in subpoenas to Barry Bonds and Jason Giambi. Heat-related deaths of the Vikings' Korey Stringer, Northwestern football player Rashidi Wheeler and Orioles pitcher Steve Bechler have been linked to ingestion of the supplement ephedra, though those cases are still winding their way through the courts.

This week, Nutraquest, a supplement company formerly known as Cytodyne, filed for bankruptcy. It is being sued by the family of Bechler, who says a Cytodyne product led to the pitcher's death in spring training.

Tom Farrey is a senior writer for ESPN.com. He can be reached at tom.farrey@espn3.com. ESPN Magazine writer Luke Cyphers contributed to this report.