The term anchor baby has gone from fringe to the spotlight, dominating political conversation on the 2016 presidential campaign trail this week.

Democrats say it's offensive, while many Republican candidates have defended its use.

Ted Cruz was asked about it by the media at the Iowa State Fair on Friday. "I think we need to stop this politically correct nonsense. We need to speak candidly about the problems facing this country," Cruz said as he continued at length about the immigration issue, although he never used the term "anchor baby" in his answers.

Experts say the phrase just the latest jargon in a long-running history of heated -- and loaded -- political rhetoric.

"It's become like one of those terms like illegal alien that people use as they are looking for shorthand as they try to talk about issues in immigration," said UCLA law professor Hiroshi Motomura, an immigration and citizenship scholar.

He also noted that language about "babies" has a long history in U.S. politics, including terms like "welfare baby" that have been used in the past.

"It also echoes some things like 'welfare baby' and things like that that make it sound like what's really going on is some strange people are having too many babies and overwhelming majority culture," Motomura said. "I think there's that image that's associated with some of these terms, like talking about people breeding too much."

He continued: "It's pithy and I think it evokes some images that -- it's a code word. It's signaling and ... it's kind of triggering images that people may really not want to get into expressly."

The term anchor babies refers to the idea that children born in the United States to non-citizen parents are automatically citizens. Users of the term and critics of birthright citizen allege that the child is an anchor baby because they can sponsor their parents for citizenship, though law prevents them from doing so until they turn 21. Term users also say the government is more lenient on undocumented immigrants with citizen children, though experts say that's debatable.

The two top candidates in Republican primary polls, mogul Donald Trump and former Florida Gov. Jeb Bush, both defended using the term this week under questioning from reporters.

Bush grew testy with a reporter on Thursday, who asked if he regretted using the term in a radio interview.

"No, I don't. I don't regret it," he said, exasperated. "Do you have a better term? OK, you give me, you give me a better term and I'll use it."

Trump was questioned about it Wednesday, responding: "You mean it's not politically correct, and yet everybody uses it? You know what? Give me a different term."

When the reporter offered child of undocumented immigrant, Trump replied, "I'll use the word anchor babies."

While other Republicans, including Louisiana Gov. Bobby Jindal, have defended using the term, some candidates have stayed away from it.

In a CNBC interview published Friday, Florida Sen. Marco Rubio said he uses "13 million human beings" when he talks about the people in the country illegally.

"Well, these are 13 million people -- those are human beings," Rubio said. "And ultimately, they're people. They're not just statistics."

Former Hewlett-Packard CEO Carly Fiorina also weighed in along those lines. "I just don't think calling human beings names ever is helpful," she told reporters in New Hampshire on Thursday.

The left has seized on the controversy, with Democratic front-runner Hillary Clinton tweeting a response to the Bush quote: "How about 'babies,' 'children,' or 'American citizens.'" Her campaign also put out a statement hitting Bush for using what her Latino Outreach Director Lorella Praeli called a "hateful term."

Motomura said he's not surprised to see Republicans latch onto a phrase that used to be mostly relegated to anti-immigration activists, because birthright citizenship has also become a much bigger issue in the race -- and GOP candidates see an opportunity to score points.

"This has become a very politically advantageous issue for Donald Trump and a lot of the Republican candidates are reacting," Motomura said. "When you really want to make your soundbite point, I think you use terms like anchor baby -- that's going to sound a lot more pithy than birthright citizenship, so it's part of the war of soundbites."

Two years ago, the Hispanic Leadership Network sent out a memo on dos and don'ts on immigration, including never using the phrase "anchor baby." Bush is on the advisory committee and was co-chairman of the group at the time.

Trump hit Bush for the about-face on Friday, tweeting

"Jeb Bush signed memo saying not to use the term 'anchor babies', offensive. Now he wants to use it because I use it. Stay true to yourself!"

In response, Bush tweeted

"His massive inconsistencies aside, @realDonaldTrump's immigration plan is not conservative and does not reflect our nation's values."

Immigration advocates say the term is still offensive.

"Ultimately, this is a term that reduces a child's existence and purpose to a gross attempt to beat the system and that vulgarly distorts the reproduction and fertility of brown skinned immigrant women as sites of political debate over citizenship," said Harvard University assistant professor Roberto Gonzalez, whose research focuses on undocumented youth. "Never mind that it would take said child 21 years to even begin the process to sponsor said mother."