A controversial amendment to the Senate defense planning bill that would allow people to carry concealed weapons across state lines has set off a firestorm on both sides of the gun control debate.
Democrats were scrambling to defeat the proposal by Sen. John Thune, R-S.D., ahead of a Wednesday vote on the measure. Thune argues the amendment, which has 21 Senate co-sponsors, will help reduce crime.
"My legislation enables citizens to protect themselves while respecting individual state firearms laws," Thune said in a written statement last week after he offered the legislation.
Opponents say the legislation would allow people to carry concealed weapons into states where they would otherwise be ineligible to do so.
"This amendment is another attempt by the gun lobby to put its radical agenda ahead of safety and security in our communities," Sen. Frank Lautenberg, D-N.J., said in a written statement.
"If you walk down the street in New York ... you can have the solace of knowing that if someone has a gun on them they've gone through a rigorous police background check. After this bill, you can have no such comfort," Sen. Charles Schumer, D-N.Y., said Sunday.
Currently, 48 states allow concealed weapons. Thune's amendment would not allow people to carry concealed weapons into the two states -- Wisconsin and Illinois -- that do not permit them.
In states that do allow concealed weapons, Thune's amendment would require anyone crossing state lines to abide by the rules of the state they are in -- such restrictions include the types of locations where a firearm can be carried.
The Brady Campaign to Prevent Gun Violence disputes the claim that allowing residents to carry concealed weapons reduces crime. It also warned that because some states have lax gun restrictions, people who've received no weapons training or who have been convicted of violent misdemeanors or sex offenses against minors would be able to carry concealed weapons across America.
Pro-gun organizations like the National Rife Association dismiss such objections as scare tactics.
"Now is the time for Congress to recognize that the right to self-defense does not end at state lines," the group said in a statement.
A Democratic aide told FOXNews.com that if passed, Thune's amendment could make it harder for the overall $680 billion defense authorization bill to pass. The aide said Schumer, Lautenberg and Sen. Dianne Feinstein, D-Calif., are trying to prevent the amendment from coming to a vote, and foes could attempt a filibuster.
Already the Senate voted to strip out funding for seven F-22 fighter jets after President Obama vowed to veto the entire defense authorization bill if the spending were included.