Women, he said, should face "some form of punishment" for getting an abortion if the procedure were outlawed.
Several hours of bipartisan outrage later, Trump did an about-face, releasing a statement in which he said those who perform abortions, and not the women who undergo them, should be punished.
But Trump's flip-flop on Wednesday was just the most recent one. Here are 10 examples:
"Biggest problem, to me, in the world, is nuclear, and proliferation," Trump told the New York Times last week.
But Trump also said that he would like to see South Korea and Japan obtain nuclear weapons, which would fly in the face of non-proliferation efforts that have been American policy for decades.
"We're better off if Japan protects itself against this maniac in North Korea, we're better off, frankly, if South Korea is going to start to protect itself," Trump said during a CNN town hall this week. "It's going to happen anyway."
Trump added, "I don't want more nuclear weapons."
2. The Iraq War
Trump steadfastly insisted throughout his campaign that he -- unlike most of his Republican counterparts -- opposed the Iraq War before it began.
"I said, 'Don't hit Iraq' because you're going to totally destabilize the Middle East," Trump said during his June 16, 2015 speech announcing his candidacy for president. "I'm the one that made all of the right predictions about Iraq."
And throughout his campaign, Trump expressed some version of that claim at nearly every campaign rally and in every interview he was asked about the issue, arguing he should get "points for vision."
But his claim was debunked in February when BuzzFeed News
dug up a September 2002 interview -- weeks before Congress voted to authorize military force in Iraq -- in which Trump said he was in favor of invading Iraq.
"Yeah, I guess so," Trump said after Howard Stern
asked him if he favored invading Iraq. "You know, I wish the first time it was done correctly."
And two days after the war began, Trump said on Fox Business Network that the invasion "looks like a tremendous success from a military standpoint."
Trump was asked by Anderson Cooper bout the contradictory statements during a CNN town hall in February.
"I mean, I could have said that," he said. "Nobody asked me—I wasn't a politician. It was probably the first time anybody asked me that question."
3. Afghanistan War
Trump also flipped his position on the war in Afghanistan, labeling the war a "terrible mistake," in a CNN interview in October.
Trump subsequently claimed that he was talking about Iraq, and not Afghanistan -- which the U.S. invaded in response to the 9/11 terrorist attacks.
But a review of the interview transcript shows that CNN anchor Chris Cuomo made it clear he was talking about Afghanistan
, mentioning the country by name twice in his question to Trump.
"We made a terrible mistake getting involved there in the first place," Trump said of Afghanistan during the October 6 interview.
And Trump himself then compared Afghanistan to the situation in Iraq.
"It's a mess. And at this point, you probably have to, because that thing will collapse about two seconds after they leave. Just as I said that Iraq was going to collapse after we leave," Trump said.
Trump's response Wednesday on punishments for abortion isn't the first time Trump has changed his tune on the issue.
But his total shift on this issue -- going from "pro-choice" to "pro-life" -- is one Trump openly acknowledges.
"I'm pro-life, and I was originally pro-choice," Trump said Tuesday in a CNN town hall. "I have evolved."
That's because in a 1999 interview and in his 2000 book as he was considering a run for president then, Trump said he was "very pro-choice," though he added in the interview that he hated "the concept of abortion."
In that 1999 interview with NBC's "Meet the Press," Trump said he would even support women's rights to "partial-birth" or late-term abortion.
Trump now wants to ban all abortions, except in the case of incest, rape or if the life or health of the mother is at risk.
5. Israeli-Palestinian conflict
Trump has sought to walk a fine line on the issue, on one hand promising his presidency would be a boon for Israel while also trying to position himself as a master negotiator who could draw the two sides of the conflict to a peace settlement.
But Trump shocked the political world when he proclaimed that he would try to be "neutral" in the conflict -- defying one of the biggest litmus tests in Republican politics.
"I want to be very neutral and see if I can get both sides together," Trump said in a December interview with the Associated Press in which he also said a peace deal will depend on "whether or not Israel wants to make the deal."
He reignited that backlash in February when he said he wants to "be sort of a neutral guy" in negotiating a deal.
But Trump's neutrality claims were nowhere to be found in a speech earlier this month during the American-Israel Public Affairs Committee's annual gathering, where he sought to place himself squarely and unequivocally in the pro-Israel camp.
"When I become president, the days of treating Israel like a second-class citizen will end on day one," Trump said.
He also excoriated what a Palestinian society he said glorifies terrorists as "heroes" and "martyrs" and proclaimed that "there is no moral equivalency" between Israel and the Palestinians.
Donald Trump declared in February that "torture works" and that he would "bring back waterboarding and I'd bring back a hell of a lot worse than waterboarding."
In subsequent rallies, Trump argued that ISIS's brutal and barbarous tactics merited a more forceful response from the U.S. that would include torturing suspected terrorists.
As experts argued that military officials would disobey even a commander-in-chief's unlawful order -- as Trump's torture decision would be -- Trump bristled.
"Frankly, when I say they'll do as I tell them, they'll do as I tell them," Trump said during a March 3 GOP debate.
The next day, Trump walked back his comments.
"I will not order a military officer to disobey the law. It is clear that as president I will be bound by laws just like all Americans and I will meet those responsibilities," Trump said in a statement that also acknowledged that the U.S. "is bound by laws and treaties."
The day after that, Trump again changed his answer again.
"We're going to stay within the laws. But you know what we're going to do? We're going to have those laws broadened because we're playing with two sets of rules: their rules and our rules," Trump said pointing to ISIS's tactics.
Donald Trump drew millions to his campaign with his bold and uncompromising pledges to build a wall on the U.S.-Mexican border and deport all of the estimated 11 million undocumented immigrants living in the U.S.
But faced with a report that he told the New York Times editorial board in an off-the-record meeting that his immigration views are in fact more flexible than he has let on, Trump appeared to confirm those suspicions.
"Everything is negotiable," Trump said in late February on Fox News when asked about the report
Trump then went on to say that he would be willing to negotiate on the height of the wall and suggested his policy to deport all undocumented immigrants could also be flexible.
Pressed by CNN the next day during a news conference as to whether deporting all undocumented immigrants was negotiable, Trump again offered a response that left the door open to changes to his policy down the line.
"At this moment, the answer is absolutely not," he replied.
8. Gun control
Donald Trump's position on the campaign trail has been clear and unequivocal. "I'm a very strong Second Amendment person," he has said repeatedly.
Trump has argued in favor of eliminating gun-free zones in schools and on military bases and argued that looser gun laws in France could have diminished the number of casualties during the Paris terrorist attacks.
But while he's argued during his running for president that he wouldn't support any further restrictions to gun access, that hasn't always been Trump's position.
Trump previously argued in favor of banning assault weapons and supported "a slightly longer waiting period to purchase a gun," a position he articulated in his 2000 book "The America We Deserve."
9. Muslim ban
Trump continues to supports his contentious proposal to temporarily ban non-American Muslims from entering the U.S. until we "figure out what the hell is going on" -- with terrorism, that is.
But the pool of people who would be banned has shrunk since Trump made the broad-based proposal that could keep as many as 1.6 billion people from entering the U.S.
Trump first described his proposal in December as a "total and complete shutdown of Muslims entering the United States." Pressed the day of the announcement for whether the policy would apply to all Muslims, Trump's campaign manager simply replied "everyone."
Later that evening, Trump said his policy would not apply to Muslims already living in the United States.
Since then he has also expanded his exceptions to include foreign leaders, government officials and business executives.
10. Hillary Clinton
Gearing up for an increasingly likely general election battle against Clinton, Trump frequently slams the Democratic presidential front-runner on the trail, including referring to her as "the worst secretary of state in the history of the United States."
Trump had previously and repeatedly heaped praise on Clinton, including in a March 2012 interview as Clinton entered the last year of her tenure as secretary of state.
Trump called Clinton "a terrific woman" in the March 2012 Fox News interview and said that "she really works hard and I think she does a good job."