Donald Trump has bagged another high-profile evangelical endorsement after Jerry Falwell Jr., president of the influential Liberty University, announced his official support.

Trump received glowing praise from Falwell when he spoke at the evangelical college last week but Falwell reserved his official endorsement until Tuesday.

"I am proud to offer my endorsement of Donald J. Trump for President of the United States," Falwell said in a statement released by the Trump campaign. "He is a successful executive and entrepreneur, a wonderful father and a man who I believe can lead our country to greatness again."

Although Trump said it was "an honour" to receive the endorsement, a number of evangelical leaders have rejected Trump's campaign, including Bob Vander Plaats.

Vander Plaats, an infuential evangelical leader in the key state of Iowa, has decided to endorse rival Ted Cruz instead of Trump. The pair are old friends and Vander Plaats told the New York Times that Trump had once offered his family a free stay in one of his hotels.

Trump, who is the strong favourite to win the Republican nomination, announced his displeasure to his 5.8 million Twitter followers.

However Vander Plaats wasted no time in coming back, saying Trump's criticism revealed his true nature.

"It's Donald Trump exposed: He wants to be your friend when he thinks he can get something in return for that friendship," said Vander Plaats in an interview on Tuesday. "In Iowa, we look at friendship as what we can do for our friends, not what our friends can do for us."

"It just shows a guy that gets tossed about to and fro too easily," he added.

"I think that kind of pride and arrogance leads to unstable temperament and judgment."

Trump has announced he will not be participating in the Republican candidates debate tonight because of an ongoing feud with the hosts, Fox News.

He demanded the news network remove anchor Megyn Kelly from hosting Thursday's debate because he said she asked unfair questions. When Fox refused, Trump announced he would not be participating in the debate and would instead host an event for wounded veterens in Iowa.

"Let's see how much money Fox is going to make on the debate without me," Trump said in a press conference, highlighting his vast ratings leverage.

Fox News responded by saying his refusal was "near unprecedented".

"This is rooted in one thing – Megyn Kelly whom he has viciously attacked since August and has now spent four days demanding be removed from the debate stage," said the network in a statement.

Kelly added: "What's interesting here is Trump is not used to not controlling things, as the chief executive of a large organisation."

"But the truth is, he doesn't get to control the media," she said.

Media agency Mediatite reported another statement from Fox, ridiculing Trump's stance:

"We learned from a secret back channel that the Ayatollah and Putin both intend to treat Donald Trump unfairly when they meet with him if he becomes – a nefarious source tells us that Trump has his own secret plan to replace the Cabinet with his Twitter followers to see if he should even go to those meetings."