Donald J. Trump fired his wunderkind campaign manager Corey Lewandowski Monday at the campaign’s regular Trump Tower meeting. “Corey was escorted out of the building,” a source close to the campaign told Breitbart News. Lewandowski came to the meeting unaware that he had lost the support of the GOP presumptive nominee, the source said. At the meeting, attended by both senior campaign staff and members of the family, Trump reviewed different campaign metrics that were all faltering: cooperation with party leaders, fundraising, surrogate operations and most importantly the polls. The campaign manager seemed to have run out of ideas. When...