Several prominent Fox News contributors, including Karl Rove, Charles Krauthammer, and Frank Luntz have recently bristled at Donald Trump's increasing involvement in the Republican primary, culminating in the debate he is moderating later this month. But any prominence or semblance of credibility Trump has this election cycle is due in large part to Fox News itself.

By all reasonable accounts, Donald Trump made a very public fool of himself earlier this year when he spent several weeks promoting conspiracy theories about President Obama's birth certificate. During that time, Fox hosted Trump repeatedly to push “questions” about Obama's birth certificate and cheered him on while he did so.

After Obama released his long-form certificate and further demolished that already-asinine conspiracy, Fox News then helped Trump run damage control.

Fox contributors like Dick Morris and Andrea Tantaros somehow decided that Donald Trump was the “winner” of the entire spectacle.

Fox & Friends, which stills hosts Trump for a weekly segment and fawns over him at every opportunity, attacked the media for being mean to poor Donald, who was just innocently trafficking in debunked conspiracy theories.

As the year went on, Fox helped Trump rewrite the history of his presidential publicity stunt, letting him pretend his hypothetical campaign was doing well when he ended it (it wasn't), and helping him broadcast that he might change his mind and actually run.

In August, despite the fact that Donald Trump's companies have filed for bankruptcy four times, Fox News shows excitedly promoted Fox host Mike Huckabee's suggestion that Trump should replace Tim Geithner as Treasury Secretary.

After months of Fox keeping Trump in the political conversation and helping rehab his credibility, Trump announced that he would be hosting a Republican debate with the conservative publication, NewsMax.

This announcement led to predictable (and reasonable) grousing from some conservatives who worried that the GOP primary was devolving into a circus, concerns that were exacerbated by Trump's announcement that he would be endorsing a candidate following the debate.

Similar to the Fox vs. Fox fight over the presidential prospects of Sarah Palin, a split is emerging at the channel over Trump's role in the primary.

Fox contributor Karl Rove has repeatedly spoken out against Trump's involvement in the debate, first calling it “weird” this past weekend, then attacking Trump yesterday morning for trivializing the election process. Last night, Rove went on Greta Van Susteren's show and again spoke out against the debate, attacking Trump as “not a newsman,” and mocking the idea that he would ask candidates about whether President Obama was born in the United States.

Fellow Fox contributor Charles Krauthammer has also had harsh words for Trump, saying that “a debate in which the moderator chooses a nominee afterwards, I think, is a reality TV show. It's not a debate, and it is a joke.”

During an appearance on Neil Cavuto's program yesterday, GOP pollster and Fox contributor Frank Luntz told Cavuto that he “think[s] it's crazy” for Republican candidates to meet with Trump, and he doesn't “know why people kiss his posterior” [via Nexis].

Yesterday, The Five co-host Greg Gutfeld mocked the Trump debate, saying, “some are calling the Donald Trump debate a side show. Others call it a circus. But I ask: why can't it be both?” [via Nexis].

But while some Fox personalities are ripping Trump, some of the biggest -- most notably Sean Hannity and the cast of Fox & Friends -- continue to defend him from attacks and lavish him with positive coverage.

Last night, an hour before Karl Rove went on Van Susteren's show to mock Trump, Sean Hannity devoted the entire first half of his show to conducting a fawning sit-down with Trump, during which Hannity helped Trump dismiss concerns about his ongoing birtherism before the two discussed whether Bill Ayers wrote Obama's first book.

Over the course of the half hour, Hannity plugged the “bold proposals” in Trump's new book, helped Trump stoke questions about whether he would eventually get into the presidential race, and announced that he would “pay” to watch Trump moderate a debate between Obama and Gingrich. This was before Hannity showed the thrilling “exclusive” footage of Newt Gingrich walking into Trump's office for their meeting.

This morning on Fox & Friends, the Trump-boosting continued. Seconds before Fox's own polling indicated that a Trump endorsement would have a negative effect on their viewers' support for a candidate, co-host Gretchen Carlson touted the importance of his support.

After a GOP strategist likened Trump hosting a debate to Snooki hosting one and saying it was “beneath the dignity of the presidency,” the Fox hosts responded by listing Trump's supposed qualifications, including co-host Steve Doocy mentioning that “he is the host of one of TV's most popular shows, The Apprentice, and he's also one of America's most successful businessmen.”

Later in the show, Fox & Friends invited Trump on to discuss his own importance, respond to critics (Rove and Krauthammer are “hacks”) and completely lie about how high his poll numbers were when he left the race. (He claims he was “leading.” He was not.)

Following the appearance, FoxNews.com teased the appearance with the headline “Who Will Get The Trump Bump?”, playing up the very ethical conflict that caused Krauthammer to criticize the debate in the first place.

If Fox contributors like Rove, Luntz, Krauthammer, and Gutfeld are upset about Trump's elevated role in the primary, they have only their employer to blame.