checks, calling them a burden on gun owners. >> i'm just wondering why the burden of my mother being gunned down in an elementary school isn't as important as that. >> i felt the enhanced improvements to our background checks system -- as you and i both know, the issue wasn't a background check system issue in sandy hook. >> erica lafferty didn't do this on her own. she was sent by the group mayors against illegal guns which helped cnn get this footage. and cnn is told billionaire new york mayor michael bloomberg's well-funded organization also plans to launch this tv ad thursday. >> senator ray yot is giving criminals a pass. >> it's shameful. >> reporter: it's one part of a coordinated effort to use this week's senate recess to keep the gun control issue alive. despite losing a pivotal vote two weeks ago to expand background checks. >> the amendment is not agreed to. >> reporter: in order to find the 60 votes needed to pass a background check bill, supporters need to change some