To Be Fair,™ these politicians know that a lot of right-wing nut jobs (who vote Republican), are probably on the terrorist watch list (Sovereign Citizens, etc.), and while they may not want to publicly acknowledge that many of their supporters are violent psychopaths, nevertheless they still wish to court their votes.
The Senate’s inaction is easily understood when you remember that white extremists are also on watch lists, and the proposed laws would make it illegal to sell guns to them, too. Laws that mean gun dealers have to say no to KKK and other White Supremists cannot be allowed to go forward, and MUST be blocked by the GOPee. The GOP strongly supports homegrown White Terrorism.