Idaho Sen. Jim Risch will appear on two national news shows tonight, CBS News with Scott Pelley at 6:30 eastern time (4:30 MT) and Anderson Cooper 360 at 8 eastern (6 p.m. MT), to discuss his threat to filibuster against gun legislation in the Senate. Risch is one of 13 senators, who also include Idaho Sen. Mike Crapo, who have signed on to a letter led by Sen. Rand Paul threatening to filibuster any gun control legislation, as Senate Majority Leader Harry Reid prepares to bring up President Barack Obama’s gun control legislative package. Yesterday, Senate Minority Leader Mitch McConnell joined the group, bringing it up to 14 GOP senators.

The letter, which Risch signed onto on March 22, says, “We the undersigned intend to oppose any legislation that would infringe on the American people’s constitutional right to bear arms, or on their ability to exercise this right without being subjected to government surveillance. … We will oppose the motion to proceed to any legislation that will serve as a vehicle for any additional gun restrictions.”

The president’s package includes universal background checks for gun purchasers and new laws against gun trafficking; amendments could address assault weapons or high-capacity magazines.