Who is Dallas King from Transfer of Power and what is their importance?

Dallas King is Vice President Baxter's chief of staff. He is described as a cocky, overbearing, scrambler and opportunist. His advice to the Vice President is questionable, as he steers Baxter towards short-sighted victory instead of long-term career health. King also leaks information to the Washington Post, which is an unforgiveable act in any situation, let alone in a time of crisis.