INDIANAPOLIS, Indiana (Reuters) - The commercial opens with an appeal to fear: a hoodie-wearing man prowling an alley, knife in hand. His face remains hidden but the ad makes it clear: He’s an illegal immigrant.

“We need tough immigration enforcement to keep dangerous criminals out,” says the ad by a national conservative political group, part of an effort to help a Republican challenger, Mike Braun, oust a Democratic incumbent in Indiana and capture a U.S. Senate seat in November’s congressional elections.

As they try to hang on to control of Congress, Republican candidates are following the lead of President Donald Trump and turning to rhetoric about immigrants as a tactic to motivate voters. The scope of that strategy emerges in a nationwide Reuters examination of ad buys, candidates’ social media posts and polling, as well as dozens of interviews with candidates, voters and campaign strategists.

The trend is especially visible on Twitter. Congressional Republicans seeking re-election have dramatically increased the number of tweets they post about immigration since Trump’s election, a Reuters/Ipsos analysis of social media shows. Immigration messaging has surged across the spectrum of Republican-held districts – highly competitive swing seats and reliably Republican ones, in places with immigrant populations both large and small.

The shift also shows up in the campaign ad wars. In races from Florida to California, in border states and ones with few immigrants, Republicans have poured millions of dollars into advertising that depict illegal immigrants as criminals and vowed enthusiastic support for Trump’s proposed wall at the Mexican border, the Reuters review shows.

This year, 20 percent of pro-Republican ads in congressional races have cited immigration, according to an analysis of broadcast advertising data through Oct. 15. That’s up from 8 percent in the same period of the 2014 congressional elections and 5 percent in the 2010 races. The analysis was conducted for Reuters by Kantar Media/CMAG, which tracks political ads.

Spending on Republican ads that mention immigration has more than doubled to $62.4 million this year from the 2014 elections and has quadrupled since the 2010 races, the Kantar Media/CMAG data shows. Immigration ad spending has also surged in state-level races. (Kantar Media/CMAG estimated earlier this month that total political ad spending for broadcast television would rise to $2.7 billion this year from $2.1 billion in 2014.)

In February, as Braun vied for the party’s nomination for the Indiana Senate seat, he ran a commercial highlighting a deadly highway crash involving a drunk driver who was in the country illegally. “There are lives at stake,” Braun said in the ad. In an interview with Reuters, he said he was not trying to demonize immigrants but was “making a point that border security is important.”

In Indiana, only about 5 percent of the state’s residents are immigrants, compared with 13.6 percent in the United States as a whole. But in the last two months, nearly a third of television ads sponsored or partially sponsored by Braun have mentioned immigration, said Michael Franz, co-director of the Wesleyan Media Project, a nonpartisan group tracking televised political advertising. Trump won Indiana by nearly 20 points in the 2016 election.

The attack ad featuring the knife-wielding immigrant was produced by One Nation, a political nonprofit. Spokesman Chris Pack said in a statement that the group works independently of campaigns and “strongly supports the efforts of the President and congressional leadership to reform our broken immigration system.”

A number of Republican ads link illegal immigrants to crime, but statistics paint a more nuanced picture. While people in the United States illegally have in some instances committed high-profile crimes, multiple studies – including ones from conservative groups like the Cato Institute - have found that immigrants commit crimes at lower rates than native-born Americans.

U.S. Election 2018 Complete coverage of the midterm elections

National Republican Congressional Committee spokesman Matt Gorman declined to comment on the overall Republican messaging on immigration, but he did say he sees benefits in opposing so-called sanctuary cities, largely Democratic-run metropolises which offer safe harbor to illegal immigrants. Dozens of localities, including New York, Los Angeles and Chicago, have joined the growing “sanctuary” movement.

Slideshow ( 9 images )

“The issue of sanctuary cities is an issue we have used in several ads this cycle. It’s a potent issue,” he said. “It’s a commonsense thing that many folks are against.”

Trump won the White House on a promise to crack down on illegal immigrants. He has tried to end a program that gave protection for illegal immigrants who were brought to the United States as children. He has ordered more aggressive enforcement and longer detention. One policy, to separate children from their parents at the southern border, set off an uproar and the president ended the policy in June.

"The issue of sanctuary cities is an issue we have used in several ads this cycle. It’s a potent issue. It’s a commonsense thing that many folks are against." National Republican Congressional Committee spokesman Matt Gorman

Trump’s administration has also limited legal immigration, imposing more restrictions on work visas and sharply cutting the number of refugees allowed into the United States.

A thousands-strong group of immigrants now heading north toward the United States from Central America has inflamed the debate over illegal immigration just days before Americans head to the polls. The caravan has riled up Trump, who is intensifying his efforts to frame the Nov. 6 elections around the threat he says illegal immigrants pose to Americans’ safety.

Trump’s nationalist tone echoes sentiments rising in parts of Europe since the arrival in 2015 of more than a million people fleeing war and poverty in the Middle East, Africa and beyond. Hungary built a border fence along its southern border with Serbia, and anti-immigration politics have roiled Germany’s parliament.

A DRAMATIC EVOLUTION

The anti-immigration rhetoric, advertisements and campaign events, combined with the party’s embrace of Trump’s immigration crackdown, represent a dramatic evolution of Republicanism under Trump. Anti-immigration themes now dominate a party that for decades was defined by fiscal, social and national security conservatism.

As recently as 2013, when the Senate passed an immigration bill with bipartisan support, a significant portion of the Republican Party backed immigration reform – including a path to citizenship for some of the 12 million people living in the United States illegally. But those voices have been mostly silenced since the rise of Trump, drowned out by his statements decrying “amnesty for illegals” and “chain migration,” his term for the longstanding U.S. policy that allows legal immigrants to bring family members into the country.

Immigration is now seen as the top issue for likely Republican voters, especially among those who are older and without a college degree, Reuters/Ipsos polling shows. Twenty-three percent of Republicans said this month immigration was the “most important problem” facing the country, up from 4 percent in January 2012. By contrast, Democrats are far more focused on healthcare, the polls show.

“Immigration is literally number one - with a bullet - in every survey we do,” said Brandon Moody, a Republican consultant at Axiom Strategies working in the Montana Senate race. Moody says the issue also serves as a kind of shorthand, signaling loyalty to Trump’s agenda.

“GREATEST THREATS”

The Reuters/Ipsos analysis of Twitter data shows that the number of Republican lawmakers tweeting about immigration has risen sharply since Trump’s election. Reuters and Ipsos searched for immigration-related terms in tweets by Republican federal lawmakers who are seeking re-election in November and have actively tweeted since 2016.

Slideshow ( 9 images )

Across 156 official Twitter accounts of Republican lawmakers and tens of thousands of tweets, the analysis identified 1,409 posts in the first nine months of 2018 which included immigration-related terms and phrases such as “immigrant,” “build the wall” or “border.” That’s a nearly 80 percent increase from 795 posts in the same months of 2017 and more than triple the number from the same period in 2016.

Reuters reviewed every tweet, weeding out those unrelated to immigration or which were entirely critical of Trump and his policies. The messages varied widely, from statements supporting Trump’s policies to nuanced calls to build a border wall while also reuniting families separated by border authorities.

The tweets ranged in tone. Some linked immigrants to threats of violence against Americans, like Texas Representative Randy Weber’s Jan. 30 tweet: “President says fix the border so gangs can’t get in & Americans won’t be murdered.”

Weber’s office declined to comment on the tweet.

Others praised Trump’s get-tough stance. “Illegal incursions way down, rule of law restored,” wrote Rod Blum, a Republican in Iowa facing a difficult re-election. He tweeted about immigration at least 14 times between January and September. Reuters did not find any tweets by Blum on the subject in 2016 and only a handful in 2017. Blum did not respond to requests for comment.

Reuters/Ipsos polling indicates that Republican lawmakers are largely preaching to the converted: 77 percent of Republican likely voters in a Sept. 8-17 survey said they supported policies to deport more illegal immigrants. An equal number backed building a wall on the southern border.

Across the 156 Republican Twitter accounts, Reuters identified only 37 tweets between 2016 and 2018 unambiguously critical of Trump’s immigration policies - almost all criticizing the separation of families at the border. The critical tweets came from 20 lawmakers who had also posted other tweets supporting strengthening border security or cracking down on illegal immigration.

Slideshow ( 9 images )

Some conservatives, while backing stringent curbs on immigration, say the harsh tone has potentially far-reaching consequences – adding to political polarization, spawning harsher enforcement and potentially limiting the party’s appeal to America’s growing minority population.

“Trump has remade the Republican Party into a blood and soil national political party that is hostile to immigration,” said Steve Schmidt, a former Republican political consultant. He left the party in June in part because of the policy of separating mothers and children at the southern border. Schmidt said the country’s growing Hispanic population ultimately will render the immigration issue “a death knell for the Republican Party.”

White House spokesman Hogan Gidley said in a statement that Trump supports an immigration system based on the merit of the applicants, which “has nothing to do with race.”

“Trump has remade the Republican Party into a blood and soil national political party that is hostile to immigration." Steve Schmidt, a former Republican political consultant.

CONFLICTED HISTORY

While Trump has thrust immigration to the center of the party’s identity, the roots of this transformation began years ago. In Indiana, the state’s Republicans have made a journey that mirrors that of the national party.

In 2006, Republican legislators pushed a plan in the state legislature that would deny public health services to immigrants who had entered the country illegally. Mike Murphy, a Republican representative from Indianapolis, rose to speak in the glass-domed statehouse.

Murphy had long worked to bring more Latinos into the party. Since many of the bill’s backers were conservative Christians, Murphy quoted verses from the gospel of Matthew about charity to outcasts and strangers. “I just turned it against them – how do you guys profess to be Christians?” Murphy said. The bill was defeated overwhelmingly.

That year, Mike Pence, a U.S. congressman from Indiana at the time, was considered a rising conservative star. He waded in with a plan to allow illegal immigrants a path to achieve legal status – though he said they would have to leave the country first. Pence pitched his plan in moral terms, calling immigration reform “a test of the character of the conservative movement.”

Pence was pilloried by hardliners, who labeled the plan a “stealth amnesty.” The bill went nowhere.

As the far-right Tea Party movement rose in the Republican Party in 2010, resentment toward immigration increased throughout the state. When a new immigration-related bill came before Indiana lawmakers in 2011, they passed it, granting police the authority to detain people suspected of being illegal immigrants. A federal judge later threw out much of the law.

“SCARY TO THINK ABOUT”

In 2015, Pence, then Indiana’s governor, signed an order that aimed to block Syrian refugees from coming to Indiana, a harbinger of Trump’s later ban on immigration from mostly Muslim countries. Pence, now Trump’s vice president, saw his order overturned by a federal appeals judge.

Pence’s spokeswoman, Alyssa Farah, said Pence has “always been for a strong, secure, enforced border and upholding the rule of law,” and that Indiana’s move to reject Syrian refugees was “fundamentally different” from the issue of illegal immigration in the southern border. “Conflating the issue of illegal immigration from our southern border with whether or not a state accepts refugees from Syria is comparing apples and oranges,” she said.

During the 2016 presidential campaign, Trump returned frequently to Indiana. At nearly every rally, he hit hard at illegal immigration, reprising crimes committed by people in the country illegally. “Raped, sodomized and killed,” he said at a rally in South Bend on May 2, 2016. “This is all over the country. We’re not taking it any more.”

Trump’s runaway win in Indiana’s presidential nominating contest a day later sealed his conquest of a crowded Republican field. Since the rise of Trump, Murphy said, it has become nearly impossible to have a civil debate about immigration. “Donald Trump made it ok to hate,” said Murphy, who is still a Republican but no longer in the state legislature.

The White House declined to comment on Murphy’s comments.

In sparsely populated Montana, almost 90 percent of the population is white and illegal immigrants are estimated to number only in the few thousands. Voter Sandy Shumaker says she was ignorant about how illegal immigration was affecting the country before listening to Trump.

Wearing an American flag hat with the slogan “Keep America Great,” the 70-year-old retired nurse said immigration is now one of her top concerns. She did not single out any specific campaign ad as a source of her thinking. Yet she echoed concerns about illegal immigrants voting for Democrats, as Trump has claimed without proof, and that Americans are being taken advantage of.

She was the first person in line for a campaign rally last month headlined by Donald Trump Jr., waiting hours to hear him stump for Matt Rosendale, the Republican challenging Democratic Senator Jon Tester.

“Open borders are scary,” Shumaker said. “Who knows what else is getting in? Drugs, I could imagine. I don’t know, Middle Eastern people that do not have our best interests at heart? It’s just scary to think about it.”