Republican presidential candidate Ben Carson speaks in Ankeny, Iowa. (AP Photo/Charlie Neibergall)

Ben Carson argued Sunday that abortion should be outlawed in almost all cases, and he likened women who terminate their pregnancies to "slave owners."

Asked on NBC’s “Meet the Press” whether a woman should have the right to terminate an unwanted pregnancy, Carson, who is running for the Republican presidential nomination, acknowledged upfront that the choice of words would be controversial.

“During slavery — and I know that's one of those words you're not supposed to say, but I'm saying it — during slavery, a lot of the slave owners thought that they had the right to do whatever they wanted to that slave, anything that they chose to do. And what if the abolitionists had said: 'You know, I don't believe in slavery. I think it's wrong, but you guys do whatever you want to do'? Where would we be?"

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Carson went on to say that he wants to see Roe v. Wade, the Supreme Court decision that legalized abortion, overturned, with little room for exceptions.

"I'm a reasonable person, and if people can come up with a reasonable explanation of why they would like to kill a baby, I'll listen," Carson told host Chuck Todd.

Carson said that an abortion to save a woman's life is "an extraordinarily rare situation," but one where "there's room to discuss" terminating pregnancy. But he would give no leeway to a pregnancy that resulted from rape or incest.

“Rape and incest I would not be in favor of killing a baby because the baby came about in that way," he said, adding that there were "many stories of people who have led very useful lives who were the result of rape or incest."

Ben Carson is a renowned pediatric neurosurgeon and Republican contender for the White House in 2016. Here's his take on Obamacare, homosexuality and more, in his own words. (Julie Percha/The Washington Post)

It was not the first time that Carson had used the imagery of slavery to illustrate a political point. His nascent political career got a boost in 2013 when, during a speech to conservative activists, he declared: "You know Obamacare is really, I think, the worst thing that has happened in this nation since slavery."

He has similarly often used Nazi metaphors in his political language. (In an interview in August, he invoked Nazi Germany to denounce Planned Parenthood.)

In Sunday's interview, when Todd asked Carson why he uses Nazi metaphors, the candidate again raised the controversy from earlier this month over his contention that if Jews in Nazi Germany had been armed, Hitler’s Holocaust campaign would have been “greatly diminished.” The comments were denounced by Jewish groups and scholars, but Carson stood by the argument, frequently used by some Second Amendment advocates in arguing against gun control.

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“Interestingly enough, in the last several weeks, I've heard from many people in the Jewish community, including rabbis, who've said you're spot on. You are exactly right. and I think it's — you know, some of the people in your business, quite frankly, who like to try to stir things up and try to make this into a big horrible thing,” he said. “And, of course, for people who aren't really thinking deeply, you know, that resonates. But the fortunate thing is a lot of people really do think for themselves, as you can see from the poll numbers here.”

Indeed, recent poll numbers show Carson overtaking businessman Donald Trump for the top spot in Iowa, which holds the first-in-the-nation contest for the GOP primary. A BloombergNews-Des Moines Register poll released Friday showed Carson leading Trump by 9 points — 28 to 19 percent.

Trump still leads the Republican field nationally. A Washington Post-ABC News poll released last week had Trump with 32 percent support to Carson's 22 percent.