Republican presidential candidate Donald Trump said Sunday that he would bring back waterboarding to fight the Islamic State of Iraq and Syria (ISIS).

Asked about the possibility of reviving back the interrogation technique, Trump told ABC's "This Week" host George Stephanopoulos, "I would bring it back."

"I think waterboarding is peanuts compared to what they'd do to us, what they're doing to us, what they did to James Foley when they chopped off his head. That's a whole different level and I would absolutely bring back interrogation and strong interrogation," he said, referring to the first American journalist who was behead by the group in 2014.

President Obama banned the practice of waterboarding and other so-called "enhanced interrogation techniques" after he took office in 2009.

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Trump also said Sunday that a protester who was shoved and kicked at his event over the weekend "should have been roughed up" because of his behavior.

"That the man...was so obnoxious and so loud, he was screaming," Trump said on "Fox and Friends" Sunday morning. "Maybe he should have been roughed up because it was absolutely disgusting what he was doing. This is not the way Bernie Sanders handled his problem I will tell you, but I have a lot of fans and they were not happy about it. And this was a very obnoxious guy, a troublemaker."

The businessman seemed to be referring to the time that Black Lives Matter activists forced Democratic presidential candidate Bernie Sanders off the stage during a rally in Seattle that was meant to celebrate the anniversary of the Social Security, Medicare and Medicaid programs.

At a Trump campaign rally in Birmingham, Alabama Saturday, a CNN reporter shot video of several Trump supporters shoving and kicking a black protester on the ground. The news outlet reported that the man was shouting "black lives matter," which was also printed on his shirt.

"Yeah, you can get him out," Trump said on stage during the rally, referring to a protester. "Yeah, get him out. Get him the hell out of here."

Although he signed a pledge not to run as a third-party candidate, Trump appears to be reassessing whether he wants to keep that possibility on the table - especially since a GOP operative is apparently plotting a "guerrilla campaign" against him, according to the Wall Street Journal.

"I'm going to have to see what happens," he said when asked on ABC if he was considering a third-party bid. "I have to be treated fairly. You know, when I did this, I said I have to be treated fairly. If I'm treated fairly, I'm fine. All I want to do is a level playing field."

"I think people are surprised that, you know, they're politicians and they've been doing this stuff all their lives. I haven't. I've been a job producer," he added. "I guess they can't understand what's happening. But what's happening is very simple. People want competence now. They're tired of incompetent people."