Donald Trump is launching an all-out attack on Ben Carson

Real-estate magnate Donald Trump has a new favourite target on the campaign trail: retired neurosurgeon Ben Carson.

The Republican front-runner has repeatedly attacked Carson since a series of polls this week showed Carson ahead in Iowa.

Trump declared during a Friday speech in Miami, Florida, that Carson is “super low-energy” and joked that he was “sleeping” when the poll was released.

“He’s very, very weak on immigration and I’m very strong on immigration,” Trump added in a CNN interview taped that day. “Ben Carson is very, very weak on immigration. He believes in amnesty strongly.”

At another rally on Saturday, Trump and said he didn’t believe the recent polls that show him losing, and ripped into Carson on various fronts.

“Who know what PACs are? It’s a crooked business. It’s a bad business,” he said. “They call them super-duper PACS. And they put up millions and millions of dollars in these PACs. And those PACs control the candidates, OK? They totally control — Carson is controlled by his PAC.”

Trump went on to hit several other top-tier candidates, including former Florida Gov. Jeb Bush (R) and Sen. Marco Rubio (R-Florida). But Trump seems particularly passionate about attacking Carson. 

At another point in his Friday speech, Trump even appeared to take a jab at Carson’s faith while discussing the Iowa polls. Carson attends a Seventh-day Adventist church, which Trump suggested was less mainstream than his own Presbyterian one.

“I get these two polls — and remember, I don’t believe them, I don’t believe them  — in Iowa. And I love Iowa. And look, I don’t have to say it: I’m Presbyterian,” he said. “I’m Presbyterian. Boy, that’s down the middle of the road folks, in all fairness. I mean, Seventh-day Adventist, I don’t know about. I just don’t know about.”

The next day on ABC’s “This Week,” Trump insisted he was not criticising Carson’s faith and would not apologise for his comment.

Watch below:

Donald Trump tells @GStephanopoulos he won’t apologise to Ben Carson after comments about his religion #ThisWeekhttps://t.co/IN3wcBO7ot
— This Week (@ThisWeekABC) October 25, 2015

Trump continued to ratchet up his attacks on Carson throughout Sunday morning.

On CBS’ “Face the Nation,” Trump further questioned Carson’s supposedly improper relationship with a super PAC supporting his candidacy. Trump, a billionaire partially self-funding his campaign, has disavowed all super PACs.

“I would imagine and those people are using that PAC differently than you’re supposed to use a PAC. They are running Iowa for him. They are in there, they’re doing all sorts of things that are totally different than what you’re supposed to be doing,” Trump said, according to a CBS transcript.

He added: “And you know, Ben is in Iowa very little, he does not go to Iowa much. The people are doing leaflets, they’re doing all this stuff. They’re essentially campaigning for him in Iowa and that’s not what a PAC is supposed to be, it’s not supposed to happen that way.”

And on “This Week,” Trump called Carson “extremely weak” on immigration, according to the show’s transcript.

“Ben is extremely weak, as you know, on illegal immigration and you can’t have that now. We have to have a country of borders. We need strength in our country. And you can’t be weak on illegal immigration,” Trump said.

Trump frequently brags that he’s a “counter puncher” on the campaign trial, only going after his rivals after they hit him first. But it appears that Carson’s support in the pair of Iowa polls  — one by Bloomberg Politics/Des Moines Register and the other by Quinnipiac University — was enough to make him a Trump target.

Trump tweeted still more criticism against Carson on Sunday morning:

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