Pete Wehner, who worked in both Bush administrations and Ronald Reagan’s White House, expressed concern that the Republican Party has become increasingly “white nationalist” while speaking to BBC presenter Emily Maitlis.
In a damning condemnation of the Republican Party, he said: “It is a more nativistic party, I think it is more of a white nationalist party than it was.
“I think there are appeals to the darker instincts and impulses that work with the base now, which wasn’t the case 10 or 15 years ago.”
The former official even suggested the US leader “embodies an anti-Christian ethic”, while talking to NBC News on Saturday.
Mr Wehner warned the Republican base is responding to an “untethered” and “unleashed” version of President Trump, and the US leader is using his rhetoric to energise his supporters.
He said: “The core base of the Republican Party right now responds to Donald Trump unleashed and untethered, and he knows that.
“So he is making an appeal using his language, and he is using his rhetoric to try and energise the base of the party.
“That is not economic, it is cultural and it is primarily geared towards immigration, and the fear of the other.”
The former official warned Trump’s “untethered” rhetoric is being copied by Republicans across the US, with numerous candidates modelling themselves on the US leader in a bid to win over the base.
He said: “What you are seeing is a lot of mini Trumps, you are seeing a lot of people who are running like Trump.
“They are calling on him to appear at their rallies, they are mimicking him, and they are fanning the flames, the same nativist flames that he is.”
While President Trump is not on the ballot on Tuesday, Ms Maitlis claimed the US leader is placing his incendiary rhetoric at the heart of the campaign because he is viewing the election as a “referendum” on himself.
She noted that Trump called on Republicans to “pretend I’m on the ballot” while speaking at a rally in Missippi.
The BBC presenter underlined that if the Democrats were to win back control of the House of Representatives, they would be able to start impeachment proceedings “pretty quickly”.
She said: “He is trying to rally his base, get out the vote, and if you like, build a wall to protect him.”