With new polls showing Ben Carson running ahead of Donald Trump in Iowa, Wisconsin and Oklahoma, Trump in recent days has turned up his rhetorical heat on his fellow GOP outsider, refusing to apologize for one jab that seemed to be aimed at Carson's religion.
On Saturday at a rally in Jacksonville, Florida, Trump told supporters that he was a Presbyterian, and then seemed to question Carson's beliefs.
"I'm Presbyterian; that’s down the middle of the road in all fairness," Trump said. "I mean, Seventh Day Adventist, I don’t know about."
Making the rounds on the Sunday talk shows, Trump denied that he was insulting Carson and/or his religion, in a bid to attract Evangelical votes in Iowa.
"Were you trying to send a dog whistle to them because Ben Carson is beating you among Evangelicals in Iowa?" asked George Stephanopolous on ABC.
"No, not at all, Trump said. "I just don’t know about that particular religion."
Trump also has repeatedly made light of Carson's low key personality, saying Carson doesn't show enough energy at his events.
Carson disputed those assertions in Iowa in recent days.
"There have been many times where I have operated 12, 15, 18, 20 hours," the retired neurosurgeon said.
"That requires a lot of energy."
Trump's attacks on Carson come as new polls show Carson surging in Iowa, where Trump has also faced television ads run by the GOP group Club for Growth, which have questioned his conservative bona fides.
Club for Growth last week also blasted Carson, questioning the basis of his own conservative beliefs.
"Ben Carson’s life story and his career in medicine are very impressive, but the full measure of his statements on economic liberty seems to indicate significant inconsistencies," the group said last week.
Carson and Trump may get to explore issues about their economic ideas on Wednesday, when Republicans gather for their next debate in Colorado, hosted by CNBC.
While Trump has dropped into second in Iowa, he remains the GOP frontrunner in national polls and in other states, as new polls by CBS and YouGov showed Trump ahead in New Hampshire and South Carolina, though those automated polls seem to skew more in favor of Trump.
Carson's campaign emailed supporters on Sunday evening in a bid for more contributions, trumpeting the polls that show him ahead of Trump in Iowa.
"Unlike the establishment candidates, he isn't running for power or fortune," the email said of Carson.
While it took a jab at Jeb Bush - ("Jeb's support of Common Core and amnesty turns off grassroots conservatives!) - Carson's fundraising note made no mention of Trump.
On Wednesday, the two men will be next to each other, front and center at the GOP debate.
The Iowa Caucuses are just over three months away.
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