Updated at 11:49 a.m. to include reaction from Minority Leader Nancy Pelosi and Hillary Clinton's campaign.
Republican presidential nominee Donald Trump declined multiple opportunities to walk back his latest charge that President Obama founded the radical Islamic State terrorist organization.
In interviews Thursday morning with CNBC and the Hugh Hewitt Show, Trump said he did not regret the charge.
"No I meant that he's the founder of ISIS. I do. He was the most valuable player. I gave him the most valuable player award," Trump told Hewitt.
Trump added later: "No, it's no mistake. Everyone's liking it. I think they're liking it."
When Hewitt said he would use "different language" to communicate a message on the Obama administration's policies, Trump responded: "But they wouldn't talk about your language and they do talk about my language. Right?"
Trump has been using the line since at least January and as recently as Wednesday at a campaign rally in Florida.
"ISIS is honoring President Obama. He's the founder of ISIS. He's the founder of ISIS. He's the founder. He founded ISIS," Trump said Wednesday. ISIS is a common acronym for the Islamic State of Iraq and Syria.
Trump added: "And I would say the co-founder would be crooked Hillary Clinton."
In a statement, Clinton campaign aide Jake Sullivan responded: "It goes without saying that this is a false claim from a presidential candidate with an aversion to the truth and an unprecedented lack of knowledge." Sullivan said Trump is "echoing the talking points" of Russian President Vladimir Putin and other U.S. adversaries.
Clinton's campaign also tweeted Thursday afternoon: "No, Barack Obama is not the founder of ISIS."
Trump also referred to the president by his full name — Barack Hussein Obama — which is often used as a dog whistle by Obama's fringe critics who believe the president is Muslim or is secretly sympathetic to Islamic terrorists.
The White House has not responded to Trump. However, House Minority Leader Nancy Pelosi, D-Calif., called Trump's comments "bizarre" at a news conference on Capitol Hill.
"It's reminiscent of demagogues who want to be in the press no matter what they have to say. They make their verbal poo poo any place to get attention. This is a tactic, this is not an accident, this is a tactic. And here we are talking about it," Pelosi said.
She also contended the 2003 invasion of Iraq "has done more to inflame the terrorists than any action you can name."
Trump's inclusion of the president ramps up an already existing line of attack he has been using against Clinton. At a Daytona Beach, Fla., rally earlier this month, Trump told supporters that Clinton's policies led to the rise of the terror group.
"Take a look at Orlando. Take a look at San Bernardino. Take a look at the World Trade Center. Take a look at what's going on, and then worldwide, and we let ISIS take this position," he said. "It was Hillary Clinton that — she should get an award from them as the founder of ISIS. That's what it was. That's what it was. Her weakness. Her weak policies."
Also on Tuesday at a rally in North Carolina, Trump labeled Clinton the Islamic State's "most valuable player."
Trump's inflammatory rhetoric is common on the campaign trail and usually a big hit with his supporters. At Wednesday's rally, the crowd cheered, "Lock her up!" in response to Trump's attack. That rallying cry was popularized at the Republican convention in Cleveland in July.
Trump described himself to CNBC on Thursday morning as a "truth-teller" when asked how he thinks these remarks play with undecided voters in battleground states. He acknowledged the possibility he could lose the race.
"All I do is tell the truth. And if at the end of 90 days, I've fallen short because I'm somewhat politically (incorrect) even though I'm supposed to be the smart one and even though I'm supposed to have a lot of good ideas, it's OK."
He added, "I go back to a very good way of life."