On-air sniping is a relatively new phenomenon for Fox News. Under longtime chairman and CEO Roger Ailes, who kept a tight rein on Fox News personalities and created a culture of fear inside the building, “people would have been too afraid to fight out in the open like that,” said a former producer. “They would not even have tried.”

“It’s survival of the fittest,” one current staffer said, describing a dynamic that tends to favor on-air personalities with the highest ratings and those most willing to engage in a public feud…

The president’s base is unlikely to abandon him, but Fox might be especially influential with “reluctant” Trump supporters whose opinions might be swayed by the coverage of the impeachment inquiry, said Sarah Longwell, a Republican strategist and the publisher of the Bulwark, a neoconservative news and opinion site.

“It’s always the most meaningful when the people who are loyalists break and oppose this president,” she said. “At a moment when he needs his staunch Republican allies, for him to do something that causes many of his staunchest allies to break with him, then that’s very significant.”