President Trump makes a promise to South Carolina voters ahead of the key runoff race to fill the seat left vacant following the death of Sen. Lindsey Graham.

President Trump makes a promise to South Carolina voters ahead of the key runoff race to fill the seat left vacant following the death of Sen. Lindsey Graham. Trump throws his support behind Graham's sister, Darlene, and offers voters a deal if she wins: he'll return to Myrtle Beach and take on the…