From the Wall Street Journal: Republican presidential candidate Donald Trump is bringing two new managers to the top of his campaign in a bid to recover ground he has lost in recent weeks. Stephen Bannon, executive chairman of Breitbart News LLC, an outspoken Trump supporter and a former Goldman Sachs banker, will assume the new position of campaign chief executive. At the same time, Mr. Trump also is promoting Kellyanne Conway, a veteran GOP pollster and strategist, to become campaign manager. Ms. Conway has been a campaign adviser for several weeks. Longtime Republican operative Paul Manafort, who joined the campaign late in the primary season, remains campaign chairman. But the reset is designed to bulk up a structure that many Republicans have complained wasn’t adequate for the rigors of the general-election campaign. […] Mr. Trump initially held to his unorthodox style and structure, arguing that they succeeded in winning the nomination. In recent days, however, Mr. Trump has been working behind the scenes to get more of what he called “firepower” atop his thinly staffed campaign organization, advisers said. On Sunday at Trump National Golf Club in Bedminster, N.J., Mr. Trump, who sought out Mr. Bannon, met with him and