On Friday, Fox News anchor Shep Smith shocked his audience and even his coworkers when he announced on-air that he would be leaving the network after 23 years.

Smith, who was an original hire for the news channel in 1996, left after publicly clashing with many Fox News opinion personalities, including Tucker Carlson.

President Donald Trump also blasted Smith on Twitter and suggested his departure was due to "terrible ratings" – which could seemingly be true, since Smith did get lower ratings than his pro-Trump colleagues.

However, Fox News insiders told CNN that Smith hadn't been pressured to leave by higher-ups, and rather, that his position on the pro-Trump network "got to be too much," leading him to negotiate an exit starting in September.

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When Shep Smith announced he would be leaving Fox News on Friday, he closed his final segment by stating that "Even in our currently polarized nation, it's my hope that the facts will win the day, that the truth will always matter, that journalism and journalists will thrive."

Privately, Fox News insiders told CNN that the Trump-friendly atmosphere at the network had "got to be too much," prompting him to negotiate an exit from his long-term contract starting in September.

Smith suggested previously in interviews, such as with Time, that he didn't know what would replace him on the network if he decided to leave. He considered himself an unbiased reporter delivering a facts-based newscast – unlike his pro-Trump colleagues, who openly use their later airtime segments to support the president's agenda.

Smith's segment is going to remain a news program, and Fox News has stated that its news anchors Jon Scott and Trace Gallagher will fill in for the interim.

President Donald Trump himself has been critical of Smith on Twitter, saying he'd rather watch "fake news" CNN than Smith's broadcast. When he learned that Smith was leaving Fox News, Trump said it was probably because of his "terrible ratings."

Smith's ratings weren't the reason for his departure. Fox News is the most-watched cable news network, and Smith beat out his 3PM time slot competitors on other networks, including CNN and MSNBC, by double-digit Nielsen Media Research ratings.

Fox News Channel anchor Shepard Smith, right, watches videos shot by his University of Mississippi journalism students, in the Fox newsroom, in New York, Tuesday, May 24, 2011. Richard Drew/AP

Shep Smith decided to leave Fox News after disagreements with the network's pro-Trump personalities, according to reports

While Smith had comparatively high ratings, his were still lower than his opinionated colleagues, like Tucker Carlson, Sean Hannity, and Laura Ingraham.

He also sparred with those later hosts, and Carlson most recently. Smith criticized Carlson for failing to defend their colleague Judge Andrew Napolitano when a guest on Carlson's segment called Napolitano "a fool."

A Fox News insider told CNN that Fox's failure to defend either Napolitano or Smith after the incident factored into his decision to leave. Early speculation online after Smith's announcement, including from Trump, left many wondering whether executives had forced him out due to his willingness to criticize the Trump administration. But insiders say Smith's managers asked him to stay.

For months, sources say the atmosphere at Fox weighed on Smith, who was one of the network's original hires in 1996. His role up until his departure was managing editor of the breaking news division, and his segment shifted from a 7 PM slot to 3 PM in 2013 so that he could, in theory, manage big news stories throughout the day.

Read more: 'Shell-shocked' Neil Cavuto reacts on-air to Shep Smith leaving Fox News, saying he doesn't know 'what the heck' the anchor is going to do next

That also contributed to a dip in ratings for Smith, and CNN reports that other hosts didn't want Smith taking over their slots, so he didn't end up having much of a role outside his new afternoon position. But news staffers told CNN that, while Smith "wasn't happy, on air and off air," those below him still considered him a role model.

Meanwhile, Fox News viewers progressively disagreed with Smith's balanced take on the Trump administration, especially compared to the bombastic, pro-Trump energy that flows throughout nighttime opinion-based segments.

After Trump was elected president, some of Fox News' other reporters left the network for the same reasons that Smith eventually did. Former chief political correspondent Carl Cameron told CNN that he gives Smith "huge credit" for staying this long.

An insider said Smith's latest contract was hefty, coming out to about $15 million a year. At one point, a former colleague said it was "all about the money" for Smith, until Trump got elected. Then it became about "holding down the mantle of journalism." Others disagreed, saying it was "never about the money" for Smith.

It's unclear what Smith's next moves will be, although his spokesperson says he will be taking an "extended" break. A Fox News insider told The Daily Beast he expects Smith to have a new job within a year, though it's also been reported that Smith signed a non-compete contract.