WASHINGTON – Invasion. Aliens. Killers. Criminals.

Those are among the words President Donald Trump repeatedly uses while discussing immigduring his campaign rallies, according to a USA TODAY analysis of the transcripts from more than five dozen of those events.

Trump, who traveled Wednesday to Dayton, Ohio, and El Paso, Texas, to meet with victims and family members reeling from mass shootings, is facing pressure from critics who say his language has fed a climate of anger toward immigrants, raising the risk of violence. A manifesto authorities believe was written by the El Paso gunman before his attack decries “the Hispanic invasion of Texas.”

But "invasion" is just one of several incendiary terms Trump regularly embraces.

A USA TODAY analysis of the 64 rallies Trump has held since 2017 found that, when discussing immigration, the president has said “invasion” at least 19 times. He has used the word “animal” 34 times and the word “killer” nearly three dozen times.

The exclusive USA TODAY analysis showed that together, Trump has used the words "predator," "invasion," "alien," "killer," "criminal" and "animal" at his rallies while discussing immigration more than 500 times. More than half of those utterances came in the two months prior to the 2018 midterm election, underscoring that Trump views immigration as a central issue for his core supporters.

He often turns to harsh rhetoric to describe gang members who are immigrants. But Trump just as often conflates the MS-13 gang, proliferating in South America and some U.S. communities, with the broader movement of immigrants across the border.

Invasion ads:Trump campaign's Facebook ads lean on talk of migrant invasion

Guns:Trump considers tougher background checks after shootings in El Paso, Dayton

Trump has used “the hell out of our country” at least 43 times during his rallies. In virtually all of those cases, he was referring to immigrants in the country illegally.

“This is an invasion,” Trump said in May during a rally in Panama City Beach, Florida. “I was badly criticized for using the word invasion. It's an invasion.”

Those who study political rhetoric question Trump’s insistence that his rhetoric is not aimed at stirring up divisions. The word invasion, some analysts have said, conjures up the image of an incursion by a foreign enemy force.

“Trump does nothing by accident,” said Ruth Ben-Ghiat, a history professor at New York University who has studied propaganda.

“The use of repetition – a propaganda mainstay – points to an intention by Trump to impose a way of thinking about his designated targets,” she said.

'Deepest, darkest forces'

Some Trump critics have pointed to an exchange between Trump and a member of the audience at the Florida rally in May who shouted “shoot them” when the president asked how to stop an influx of people crossing the border he described as a "crisis."

“That's only in the Panhandle you can get away with that statement,” Trump joked.

But while that exchange drew significant attention from national media, it captured only a slice of the harsh rhetoric Trump regularly relies on during his rallies.

“The words of a president matter,” former vice president and Democratic presidential candidate Joe Biden said Wednesday in Iowa. “They can unleash the deepest, darkest forces in this nation. That is what Donald Trump has chosen to do.”

Trump has rejected the idea that his words have inspired violence.

Trump accused those raising the criticism of trying to score political points ahead of the 2020 election. He has pointed to other shooters, including the gunman in Dayton, who appear to have supported Democratic candidates.

“I think my rhetoric ... brings people together,” Trump told reporters at the White House before departing on the daylong trip to Ohio and Texas. “I think we have toned it down. We’ve been getting hit left and right from everybody.”

The United States has a deep history with violence directed at ethnic and racial minorities that predates Trump. It's also true that other mass shooters have indicated support for Democrats. But the president's rhetoric is unusual in the intensity he brings to his attacks. Even Trump's supporters acknowledge he speaks differently than most politicians. For some, that’s part of his appeal.

For others, it's cause for concern.

Trump was tweeting the term “invasion” to describe illegal immigration at least as far back as August 2015, when he appears to have quoted a supporter demanding that he "stop the invasion." But Trump's use of the word came under added scrutiny after the gunman in the deadly shooting at a Pittsburgh synagogue last fall posted a gripe about "invaders."

Still, Trump continued to hammer away on Twitter and at his rallies with the word “invasion," or some variation of it. He used the word at least four times in two separate rallies on Nov. 4, two days ahead the 2018 midterm election. There is no indication the synagogue shooter, who was critical of Trump, was responding to Trump's rhetoric.

Trump used the word again during a rally in Iowa in March, telling supporters the nation was "on track for 1 million illegal aliens trying to rush our borders. It is an invasion."

Immigrants v. MS-13

Trump’s most vitriolic rhetoric – “killers” and “predators,” among other words – is virtually always reserved for members of the MS-13 gang. It is gang violence that many people arriving in the U.S. are seeking to escape by claiming asylum.

But as far back as his campaign, Trump has often conflated gangs with broader immigration. Some studies suggest immigrants in the country illegally are far less likely to commit crimes than citizens, in part because to do so risks capture and deportation.

That's a distinction Trump never raises, and it's a nuance that can be lost in sharp, easy-to-digest soundbites.

“We have barbed wire going up because you know what? We're not letting these people invade our country,” Trump said during a rally in Macon, Georgia, in November.

“ICE is tracking down gang members, drug dealers, predators and killers, and we're either throwing them in jail or throwing them the hell out of our country,” he said in Charleston, West Virginia, months before that.

Trump launched his White House run in 2015 with a speech alleging that foreign countries were "sending people that have lots of problems" including, he said at the time, "rapists." But Trump dropped the word from his rally stump speech before he became president. It has occasionally cropped up during official events on immigration, including in January.

Nearly three of four Democrats say some of the responsibility for recent violence lies with the president, according to a USA TODAY/Ipsos Poll this week. That compares with 23% of Republicans who feel that way.

Poll:Who's to blame for mass shootings? On that, some bipartisan agreement

'Dehumanizing rhetoric '

Some experts say the president's language has created a charged atmosphere that can increase the possibility of violence.

"President Trump’s dehumanizing rhetoric about those seeking entry at the southern border creates a climate conducive to hostile action," said Kathleen Hall Jamieson, a professor of communication at the University of Pennsylvania.

Beyond the rally stage, Trump’s campaign has flooded social media with warnings that the U.S. is under “invasion” by immigrants coming across the southern border. That has taken place on Twitter, the president’s platform of choice, but also in a deluge of advertising on Facebook.

Facebook political advertising data analyzed by USA TODAY shows that Trump’s campaign funded the publication of more than 2,000 political ads that urged users to, for instance, “STOP THE INVASION.”

Another word Trump has frequently used to describe immigrants is "alien." He was nearly four times as likely to use that word when describing immigrants during his rallies than “immigrants,” according to the analysis. He almost never uses the word “migrant.”

“Alien” is a word occasionally found in federal law or official documents, but it has not been uttered as frequently by Trump’s predecessors, if at all. A review of former President Barack Obama's remarks and statements archived at the American Presidency Project at the University of California Santa Barbara found no reference to the term. A similar review for President George W. Bush’s term found only a handful of references to the word.

“Some in this country argue that the solution is to deport every illegal immigrant, and that any proposal short of this amounts to amnesty,” Bush said during an address to the nation on immigration in 2006, using language that was more representative of how he generally talked about immigrants.

“It is neither wise, nor realistic to round up millions of people, many with deep roots in the United States, and send them across the border,” he said.