***UPDATE*** Gabriel Sherman of New York Magazine suggests that Corey Lewandowski was fired at the urging of Trump’s children. Via New York Magazine:
Earlier Monday morning, Donald Trump and his adult children gathered for a regular strategy meeting at Trump Tower. Also present was Corey Lewandowski, the campaign’s embattled manager. According to one senior Trump staffer briefed on the meeting, “things went south for Lewandowski, and he was fired.” Shortly after, he was escorted out by security. Paul Manafort, Trump’s campaign manager, is now fully in charge.
Lewandowski’s ouster was the result of a coup led by Trump’s children Ivanka, Eric, and Donald Jr., according to the staffer. And his abrupt dismissal culminates one of the most dramatic story lines of the 2016 campaign.
Donald J. Trump is parting ways with his campaign manager, Corey Lewandowski, a move that comes as the presumptive Republican nominee faces challenges as he moves toward the general election.
“The Donald J. Trump Campaign for President, which has set a historic record in the Republican primary having received almost 14 million votes, has today announced that Corey Lewandowski will no longer be working with the campaign,” the campaign spokeswoman, Hope Hicks, said in a statement. “The campaign is grateful to Corey for his hard work and dedication and we wish him the best in the future.”
Mr. Trump had faced increasing concerns from allies and donors, as well as his children, about the next phase of the campaign as he pivots toward a general election.