LAS VEGAS - Donald J. Trump has shaken up his presidential campaign for the second time in two months, hiring a top executive from the conservative website Breitbart News and promoting a senior adviser in an effort to right his faltering campaign.
Stephen Bannon, the executive chairman of Breitbart News LLC, will become the Republican campaign’s chief executive, and Kellyanne Conway, a senior adviser and pollster for Mr. Trump and his running mate, Gov. Mike Pence of Indiana, will become the campaign manager.
