U.S. Rep. Roy Blunt, R-Mo., the House Majority Whip, said Gaston, a longtime aide, takes over for chief of staff Dave Hebert on Friday.
Sources told UPI Hebert had developed a reputation for being a disruptive influence within the Whip operation.
Gaston, a former aide to retired House GOP leader Dick Armey, R-Texas, is a longtime congressional veteran.
"Roy Blunt has just strengthened his team considerably," Washington lobbyist Dennis Stephens said. A former House GOP aide, Stephens said leading the Whip's staff is "one of the toughest jobs in Congress, akin to herding cats. Brian has all the right stuff to do it well."
Describing Gaston as a trusted member of his staff, Blunt said: "The entire Whip operation will benefit from his policy expertise, incredible institutional knowledge and wealth of contacts."