Ailes was already concerned about Rubio's lackluster performance in GOP primaries and caucuses, winning only one contest among the 15 that have been held.
But the more proximate cause for the flip was an embarrassing New York Times article revealing that Rubio and Ailes had a secret dinner meeting
in 2013 during which the Florida senator successfully lobbied the Fox News chief to throw his support behind the "Gang of 8" comprehensive immigration-reform bill.
"Roger hates seeing his name in print," a longtime Ailes associate told me. "He was appalled the dinner was reported," the source said.