President Trump used the phrase "illegal alien" four times in 10 minutes during his first prime-time Oval Office address. (Mandel Ngan/AFP/Getty Images)

President Trump’s rhetoric on immigration has been contentious from Day One of his campaign — literally. He rode down that golden elevator in Trump Tower and declared undocumented immigrants to be “criminals,” “rapists” and drug-pushers. He commenced a campaign in which crimes committed by undocumented immigrants would take center stage. Separately, he called for a total ban on immigration by Muslims. As president, his administration forced the separation of families at the border, before a backlash pushed them to reverse course.

But through it all, even Trump largely avoided an antiquated phrase for these immigrants — until now, that is.

Even as politicians and the media have increasingly shifted away from the phrase “illegal immigrant” and toward “undocumented immigrant,” Trump over the past several months has taken a hard turn in the other direction. With increasing regularity, he is employing the phrase “illegal alien” — a term that appears throughout the legal code but has been almost completely absent from the words of politicians in recent years.

According to Factba.se’s tracking of Trump’s public comments, he used the phrase in his own words twice in 2015 and five times in 2016 — a total of seven times as a candidate, even as he was campaigning hard and talking about illegal immigration nearly every day. Then he used it only twice in his first year as president. That’s nine total mentions in two and a half years.

Over the past six months, though, Trump has used the phrase on at least 35 different occasions. It all culminated last week when he used the phrase four times in 10 minutes in his first prime-time Oval Office address. He also tweeted it three times over the weekend, including twice in someone else’s words and once in his own — only the third time he has used the phrase on Twitter without quoting someone else.

The reason for the rhetorical shift from “illegal alien” to “illegal immigrant” was similar to the reason for the shift from “illegal immigrant” to “undocumented immigrant.” While many politicians (mostly Democrats) have decided people can’t be “illegal” — even if their method of entry was — almost all politicians have made the decision that “alien” unfairly connoted invaders who were not human.

A Pew Research Center study in 2013 found that just 5 percent of newspaper references used the term “illegal alien” — down from about 1 in 5 references in both 2007 and 1996. The study was conducted as news organizations were shifting from “illegal” to “undocumented."

The law, though, still refers to “illegal aliens,” and the Justice Department last year (under the guidance of immigration hard-liner Jeff Sessions) issued guidance making sure U.S. attorneys used the phrase. And a president who has shown an ability to move the public discourse appears to be trying to resurrect an old-fashioned phrase — in the service of pursuing an old-fashioned solution to illegal immigration.