Gannett Co. is poised to merge with rival GateHouse Media in a potential deal linking the nation’s two largest newspaper groups, The Wall Street Journal reported Thursday. Under terms of the proposed cash-and-stock deal, which the WSJ said could be announced in the coming weeks if all goes right, GateHouse’s parent would likely buy Gannett and GateHouse Chairman and CEO Mike Reed would assume the same roles at the enlarged entity.