U.S. National Accelerator R\&D Program on Future Colliders

Future colliders are an essential component of a strategic vision for particle physics. Conceptual studies and technical developments for several exciting future collider options are underway internationally. In order to realize a future collider, a concerted accelerator R&D program is required. The U.S. HEP accelerator R&D program currently has no direct effort in collider-specific R&D area. This shortcoming greatly compromises the U.S. leadership role in accelerator and particle physics. In this white paper, we propose a new national accelerator R&D program on future colliders and outline the important characteristics of such a program.