“I know maybe the president is watching.”

So said Brian Kilmeade, co-host of “Fox and Friends,” on Thursday morning’s show. It was no mere boast, since President Trump has publicly stated his affection for the show and for Fox News, the channel on which it airs. If Mr. Trump was indeed tuning in, he was far from alone. Fox News has been the most watched cable news network for 15 years, but depending on the hour, the news narrative it presents to its large and loyal conservative audience can sharply diverge from what consumers of other media outlets may be seeing.

We watched Fox News from 6 a.m. until midnight on Thursday to see how its coverage varied from that of its rivals on a day when cable news was dominated by the health care debate in Congress, the terrorist attack in London and the investigation into Russian interference in the presidential election.

One notable way Fox News stood apart from its competition, as it has been known to do for years, was in the stories it chose to highlight and the tone — in some of its opinion shows, unapologetically supportive of Mr. Trump and his agenda — with which it covered them.

There was extensive coverage of the health care vote, for example, but there was also considerable time given to topics, like a rape case in Maryland, that viewers would not have heard about if they had turned to CNN or MSNBC. The rape case, which involved an undocumented immigrant and went virtually uncovered on most networks, received almost hourly updates on Fox, and at times was used as proof that Mr. Trump’s calls for tighter borders and a crackdown on immigration were justified.