NEW YORK • It started with Ms Megyn Kelly's interrogation of Republican presidential hopeful Donald Trump at last Thursday's debate on Fox News.
Mr Trump responded, in less than presidential terms. The network's chief executive, Mr Roger Ailes, intervened, placating Mr Trump while also defending his star anchor, Ms Kelly.
If this sounds like a war, it is an unconventional one. It is not mutually assured destruction; it is mutually beneficial combat.
With his disregard for the rules of politics and public discourse, Mr Trump has become a runaway train that no one can stop - or stop watching. Post-debate polls show the real-estate magnate holding his lead over his Republican rivals, even as he insisted he will "keep the door open" to a potential independent run.
But the surveys also show that voters are increasingly uncomfortable with his aggressive temperament. A new Suffolk University poll in Iowa, which holds the first presidential contest early next year, has Mr Trump leading with 17 per cent, Mr Scott Walker, governor of neighbouring Wisconsin, second with 12 per cent and Senator Marco Rubio of Florida with 10. It also showed Mr Jeb Bushin seventh spot, compared with his RealClearPolitics average of third position in Iowa over the past month.
But 55 per cent of Suffolk's respondents said Mr Trump's debate performance made them "less comfortable" with him as a presidential candidate.
The Fox telecast of the Republican debate, with Mr Trump centre stage, was the highest-rated presidential primary debate ever. Yet his improbable candidacy is also more than a little perilous.
To demonstrate its seriousness about vetting the Republican candidates, the network subjected Mr Trump to rigorous questioning, as Ms Kelly did. Yet Fox cannot afford to alienate Mr Trump - or the network's core audience which view it as an alternative to a media they see as leaning left. If the network pushes Mr Trump too hard, it risks being seen as part of the mainstream, rather than its antidote.
"The big question mark is how sensitive do Republicans have to be about criticising Trump or about reining Trump in," said Mr Jonathan Klein, former president of CNN. "I don't think anyone knows."
Complicating the matter is a history of enmity between Mr Trump and Mr Rupert Murdoch, the founder of 21st Century Fox, which owns the network.
But the battle between Mr Trump and Ms Kelly has been something else; Ms Kelly was pressing Mr Trump not on politics but on his treatment of women. Mr Trump's response the following night on CNN - that she had "blood coming out of her wherever" - went into uncharted political waters. (Mr Trump has since said it was not a reference to menstruation.)
In assuming such an aggressive posture towards the Republican front-runner, Ms Kelly is either expanding the idea of what Fox News can be or bumping up against its ideological constraints.
NEW YORK TIMES