Marjory Stoneman Douglas to require clear backpacks, locked classroom doors
McCaskill zings GOP senator over car incident
"Probably the only shot you've got to take me out!" she yelled at the driver of the golden sedan, which NBC News's Kasie Hunt identified as belonging to Gardner.
Gardner heads the National Republican Senatorial Committee (NRSC), the Republican party's campaign arm for the Senate, which is backing GOP challengers in Missouri against McCaskill.
The NRSC is backing Josh Hawley, Missouri's attorney general fighting for the party's nomination in the race to unseat McCaskill in 2018, and has released a series of vicious attack ads against the two-term Democratic senator.