Sens. Dick Durbin of Illinois, Richard Blumenthal of Connecticut, Sherrod Brown of Ohio, Ed Markey of Massachusetts, Tom Harkin of Iowa, Barbara Boxer of California, and retiring-Rep. Henry Waxman of California wrote that e-cigarettes should be treated the same way as cigarettes. (Cigarettes are currently banned at the Capitol, nearby office buildings, and within 25 feet of the entrance of the buildings.)

In the letter, the group of Democratic members of Congress says that while it’s unclear whether or not e-cigarettes are safer than traditional cigarettes, banning them would be “an appropriate precautionary step to promote public health and maintain a safe environment for staff and visitors of the institution and its grounds.”