Major League Baseball players have authorized their union to negotiate a tougher policy on steroid use. The move comes as the U.S. Senate is threatening to take action, and two of baseball's leading home run hitters are surrounded by a cloud of controversy.

After a four-hour meeting with 40 players in Phoenix, Arizona, Tuesday, Players' Union head Donald Fehr said the union's executive board had authorized him to attempt to negotiate an agreement on steroid testing.

Fehr will take the unprecedented step of opening the players' collective bargaining agreement to amend the steroid policy. Fehr said he expects the new agreement to be in place quickly.

"The public and the fans are always among the players' highest concerns. But we have to negotiate an appropriate agreement," he said. "I think we will. I don't think it will take an extended time."

Fehr made the point that the potential amendments to the agreement had nothing to do with recent revelations that star hitters Barry Bonds of the San Francisco Giants and Jason Giambi of the New York Yankees used steroids. Bonds has denied knowingly taking the drugs while Giambi admitted taking human growth hormone.

Former Los Angeles Dodgers' manager Tommy Lasorda says that the revelations by Bonds and Giambi have hurt the game. Lasorda says players should be more forthcoming about drug use.

"I think it is a real black mark against baseball right now, for all this stuff that is coming out," he said. "If none of them take it [steroids] then they should be willing to take a test any time anywhere."

The move comes as the Senate Commerce Committee chairman, Senator John McCain of Arizona, is threatening to introduce legislation that would force stronger testing if players and owners do not amend their policy.

Baseball's current policy puts players in a treatment program for a first offense. Players face stiffer penalties, including suspensions and fines, for further infractions.

Donald Fehr says that while he believes that baseball's current testing program worked well, he is open to changing the policy.

"The testing program we had this year had some pretty significant positive effects," he said. "That does not mean, however, that given the experience we have had, that there cannot be amendments, which could even be better than that."

President George W. Bush - a former baseball team owner - has weighed in on the controversy. Mr. Bush called for the elimination of steroid use in sports in his State of the Union message last January.

In light of the recent revelations, White House spokesman Scott McLellan said Mr. Bush believes Major League Baseball and the players must act to resolve what he called "a serious problem."