Baseball's collective bargaining agreement between the player's union and owners expires in December, offering the opportunity for renegotiation of rules, compensation and conduct policies. Baseball's commissioner has already agreed to the ban, but players have been hesitant.

The senators argue that use in games is an implicit endorsement of tobacco use to the children watching games.

“Major League ballplayers who use smokeless tobacco at games are providing a celebrity endorsement for these products, encouraging many young people to try smokeless tobacco," the senators wrote.

The Center for Disease Control says that the use of smokeless tobacco is dangerous — and on the rise. A 2009 survey found that 15 percent of high school boys used smokeless tobacco, up from 11 percent in 2003. That number is expected to grow as states place more restrictions on smoking indoors.

“Major League Baseball and the players union should follow the senators’ leadership and get smokeless tobacco out of the game,” Matthew L. Myers, president of the Campaign for Tobacco Free Kids, said in a statement. “Now it is time for baseball to act to protect the health of current players and millions of kids who look up to them.”