The Republican National Committee announced late Thursday that the venerable conservative magazine National Review had been dropped as a debate sponsor after it published an issue devoted to why voters should reject Donald Trump's presidential campaign.

RNC spokesman Sean Spicer confirmed to Buzzfeed News that the magazine had been dropped as a sponsor of the Feb. 25 debate in Houston, saying "a debate moderator can't have a predisposition."

"We expected this was coming," National Review publisher Jack Fowler wrote in a blog post early Friday, calling the RNC move a "small price to pay for speaking the truth about The Donald."

The move by the RNC leaves CNN, Salem Media and Telemundo as the remaining debate sponsors. Earlier this week, the RNC announced that it had severed ties with NBC, the previously scheduled debate host, due to dissatisfaction with the way the network conducted a debate on CNBC this past October.

The National Review issue, described as a "symposium", featured a collection of scathing anti-Trump essays from noted conservatives, underscoring the deep resistance that remains to his unorthodox candidacy, despite his commanding lead in early polls.

Three of the National Review essays came from Fox News contributors Katie Pavlich, Erick Erickson and Cal Thomas.

"Trump’s liberal positions aren’t in the distant past—he has openly promoted them on the campaign trail," Pavrich wrote. "Trump isn’t fighting for anyone but himself, which has been his pattern for decades."

At an event in Las Vegas late Thursday, Trump described the magazine "a dying paper" out for publicity. Ironically, Trump named the magazine's late founder, William F. Buckley Jr., during last week's Republican debate as an example of a conservative who came from New York in response to Sen. Ted Cruz's jibe about Trump representing "New York values".

Trump also claimed Thursday that Republican powerbrokers are "warming up" to his candidacy.

"I want to be honest, I have received so many phone calls from people that you would call establishment, from people — generally speaking ... conservatives, Republicans — that want to come onto our team," Trump told reporters in Las Vegas before an appearance at the Outdoor Sportsman Awards, also announced the endorsement of "Duck Dynasty" star Willie Robertson.

"We are getting calls from everybody that it's actually amazing. I'm actually surprised," he added. He declined to provide names.

The Associated Press contributed to this report.