The U.S. Senate will vote today on an measure that would the nation’s 5 million people with concealed weapons permits in one state use their weapon in another state, a move which critics say would water down gun laws in stricter states.

The outcome of the vote is uncertain at this point, according to the Associated Press. The law would allow movement by individuals in 48 states, excepting Illinois and Wisconsin which don’t have concealed weapons laws, AP reports. Permit holders would still have to obey the laws of other states, such as weapons bans in certain places.