(CNN) Under fire now over a racially charged tweet, Rep. Steve King, the Iowa Republican, has for years stirred controversy with a string of controversial remarks about race, immigration and the effects of demographics on American culture.

King on Sunday praised prominent Dutch nationalist politician Geert Wilders, writing in a tweet that the far-right candidate "understands that culture and demographics are our destiny. We can't restore our civilization with somebody else's babies."

Wilders understands that culture and demographics are our destiny. We can't restore our civilization with somebody else's babies. https://t.co/4nxLipafWO

Asked what he meant during an interview with CNN's Chris Cuomo on "New Day" less than 24 hours later, King doubled down -- and elaborated: "You cannot rebuild your civilization with somebody else's babies. You've got to keep your birth rate up, and that you need to teach your children your values."

For those who have followed the Iowa congressman's career, the comments were stunning -- if not particularly surprising. King has long spoke in degrading terms about immigrants and minority groups.

'Cultural suicide'

@FraukePetry Wishing you successful vote. Cultural suicide by demographic transformation must end. @geertwilderspvv pic.twitter.com/Kp6uieaMDG — Steve King (@SteveKingIA) September 18, 2016

In September 2016, King offered his support to far-right German politician Frauke Petry, the chairwoman of the Alternative for Germany party.

"Wishing you successful vote," he tweeted, tagging Wilders. "Cultural suicide by demographic transformation must end."

AfD has been a vocal critic of Chancellor Angela Merkel's refugee policy, and declared -- months earlier -- in a party manifesto that "Islam is not part of Germany."

'We do that with livestock'

King constructed a mock border wall on the House floor in 2006. After he snapped a series of blocks together, he suggested putting wire on the top to discourage people who might try to scale it.

Still, there was more: "We could also electrify this wire with the kind of current that wouldn't kill somebody, but it would simply be a discouragement for them to be fooling around with it," he said. "We do that with livestock all the time."

'They've got calves the size of cantaloupes'

King in 2013 explained his opposition to the DREAM Act, a bill that would have put young undocumented immigrants brought into the US by their parents on a path to legalization, by suggesting that it would open the border to good students and drug mules in equal measure.

"For every one who's a valedictorian, there's another 100 out there that they weigh 130 pounds and they've got calves the size of cantaloupes because they're hauling 75 pounds of marijuana across the desert," he told Newsmax.

'A rape path'

During a 2014 interview with CNN's Chris Cuomo, King stated -- without evidence -- that the parents of young girls sent to north to enter the US along its southern border had been giving them "birth control pills" ahead of the trip.

"This is a man-caused disaster, and the man that caused it is Barack Obama," King said , calling the former president's immigration policies an "advertisement that has been such a huge magnet that have caused these families to give their daughters birth control pills and send them down a rape path all the way through Mexico. And that's a death path on the death train too."

'A continental origin'

During the 2014 unrest in Ferguson, Missouri, King was asked on Newsmax about calls by the Congressional Black Caucus for the Justice Department to investigation racial profiling by local police.

"This idea of no racial profiling," King said, suggesting that none was necessary, "I've seen the video. It looks to me like you don't need to bother with that particular factor because they all appear to be of a single origin -- I should say, a continental origin might be the way to phrase that."

'There's nothing for us to apologize for'

In August 2015, King spoke to a Minnesota talk radio host about his burgeoning support for then-candidate Donald Trump and how, as he put it, still-President Obama had created the an environment for Trump to succeed.

"They've delighted in dismantling our military, and it seems as though (Obama has) apologized to every continent out there," King said in comments flagged by Right Wing Watch

"You know, he apologized to Africa for slavery," King added (falsely), "and genuflects to the Arabic princes and genuflects to the emperor of Japan, and it goes on and on. Americans are tired of apologizing ... We're a proud people. We're the vigor of the planet and there's nothing for us to apologize for until they come and thank us for the things we've done."

'She didn't change the course of history'

JUST WATCHED Trump on Tubman $20: 'pure political correctness' Replay More Videos ... MUST WATCH Trump on Tubman $20: 'pure political correctness' 03:31

King in 2016 tried -- and failed -- to pass an amendment that would have blocked the Treasury Department from replacing President Andrew Jackson on the $20 bill.

Asked about his attempt to block the change, King told CNN he didn't believe abolitionist Harriet Tubman's work warranted it.

"As much as she did," the congressman said, "she didn't change the course of history."

The House Rules Committee ultimately decided the amendment had not been properly drafted and scrapped it before members would have to vote.

'These other categories of people'

During the Republican convention in Cleveland last summer, King on MSNBC responded to Esquire political columnist Charles Pierce's observation that, with Trump's nomination, 2016 could be "the last time that old white people would command the Republican Party's attention, its platform, its public face."

King said: "This whole 'old white people' business does get a little tired, Charlie. I'd ask you to go back through history and figure out where are these contributions that have been made by these other categories of people that you are talking about? Where did any other subgroup of people contribute more to civilization?"

"...than white people?" host Chris Hayes asked.

"Than Western civilization itself," King said. "It's rooted in Western Europe, Eastern Europe and the United States of America and every place where the footprint of Christianity settled the world. That's all of Western civilization."

'You get the pick of the litter'

During a 2012 campaign event in Iowa, King delivered a rambling disquisition on American immigration history.

"You put out a beacon like the Statue of Liberty and who comes here? The most vigorous from every country that has donated legal immigrants to the United States of America," he began. "The cream of the crop."

King then compared the current situation to his family's system for sorting dogs:

"We've always had bird dogs around our place. In our family there's a black lab and white lab, a yellow lab, and my brother has a chocolate lab. You go in and you look at a litter of pups, and you watch them. You watch how they play — they run around a little bit — and what do you want? You want a good bird dog, and you want one that's gonna be aggressive? Pick the one that's the friskiest, the one that's engaged the most — not the one that's over there sleeping in the corner. You want a pet to sit on the couch, pick the one that's sleeping in the corner. So, you get the pick of the litter, you got yourself a pretty good bird dog. We got the pick of every donor civilization on the planet because it's hard to get here, they had to be inspired to come. We got the vigor from the planet to come to America. Whichever generation it was, and then we taught our children that same thing."