In the final days before the US Senate elections in Alabama last December, President Trump turned to his favorite subject.
"We will have borders at the border," he said. A few months later, before a special congressional election in Pennsylvania, he proclaimed: "The Democrats are the party of the protectorates … they like to protect criminals."
He turned back to him in Ohio in August, when he campaigned for a Republican candidacy in a special election in the House of Representatives. "A vote for … The Democrats are voting to let criminals and drugs flow into our country," he said.
Now it's the caravan.
During the last stage of each campaign since taking office in 201
The present caravan has given him an impressive picture of a group of immigrants slowly approaching the border. He has called the crowd the Middle East who are potential terrorists – later he admitted that there was "no evidence" for it.
On Thursday, his government announced it would send 800 troops to the border. The White House also considered closing the border and denying Central Americans in the caravan the opportunity to seek legal asylum in the United States.
It is an attempt to dominate the conversation, which floods ether waves directly, even if the group of immigrants is still about 1,000 miles from the US border.
The White House has, according to people who are familiar with the call, a daily call to the caravan with officials from the administration and the Congress. White House and Republican Party officials are also urging surrogators to talk and talk on television.
The president himself has repeatedly focused on the caravan.
"As we speak, the Democratic Party Caravan after Caravan encourages illegal aliens who are breaking our laws and breaking into our country," Trump said Wednesday evening during a rally in Wisconsin.
He also claimed that unnamed American cities are being liberated by violent immigrants and residents in these unnamed cities are gathering windows to applaud American immigration agents
"I tell you, it's like watching World War II films ", he said. "It's like seeing documentaries about World War I and WWII, the professions, they get them, they take them out, and people stand on their windows, they clap and scream and they're happy."  So far, the president is fighting a one-sided fight. Most Democrats choose not to get involved, but focus instead on health care, a topic that they think is more important to voters.
Democratic group American Bridge received an eye-catching email on Thursday stating "Kanye Traveling to the Caravan." But the content of the email was about Republicans and pre-existing health conditions.
"To be honest, as an immigration advocate, I think most Democrats are smart enough not to get entangled in Trump's environment and stay true to the theme that [race races] use [it]," said Frank Sharry, executive director the immigration office America's vote. "Do you want to rudely discuss homestretch policy over Trump in a caravan 1,000 miles away, or 130 million Americans in pre-existing conditions who might lose their protection?"
"You do not have to get involved A deep debate on immigration policy, two weeks before half-time, at this point," he added. "Trump just wants to demagogue the topic."
Democrats and immigration advocates point to the limitations of Trump's vocation. Many of the candidates for which he ran in previous elections lost. During the 2017 Florida governor's race, Republican candidate Ed Gillespie also turned to immigration in the final weeks of the election campaign, attempting to link the gang violence of the MS-13 with the electoral right of Democratic candidate Ralph Northam to ban sanctuary towns.
I'm not very frustrated with him, "Sharry of Northam said. "Why does not he get up and talk about immigration, damn it?" But he stuck to his "I am a doctor who takes care of the health and I will stick to it and be as boring as possible".
He won 9 points.
Trump told White House advisers that immigration is an issue where Democrats have "no message," a senior White House official says.  A good message in it is a simple contrast, "said the senior official.
Republicans consider the general immigration issue as having power across the country that can motivate Trump supporters, especially white men, and put fear into the thoughts of independents. You've placed ads in Sanctuary cities in Minnesota, Pennsylvania, and California. In North Dakota, almost as far from the Mexican border as any other state, many Republicans have sought protection cities.
"That's a big factor," said Matt Gorman, a spokesman for the National Republican Congressional Committee. "Immigration – even before the caravan – was a topic that arose for months in districts, not even near the border."
In a national Washington Post-ABC News poll earlier this month, 16 percent of registered voters saw immigration as one of the key issues of their choice; It left other issues such as the economy, health care and equal treatment of men and women.
Respondents gave Congressional Democrats an 11-point lead over Trump whom they trust more to deal with immigration. But Trump is doing better when it comes to border security. A Washington Post-Schar School opinion poll in July revealed that Americans Trump trusted the Democrats in Congress with an eight-point lead when they were asked which border security was better. His advantage rose to 17 points in Congressional Battlefield districts, which lean more Republicans.
"Border security is a real concern among the voters, and the caravan raises the issue at a pretty important time," said Neil Newhouse, a Republican pollster. "And it has an impact because border security is already an issue in this election."
Republicans believe the argument resonates most in border states, including rival contests in Texas and Arizona.
In Indiana, Republican Mike Braun's campaign repeatedly refers to Senator Joe Donnelly (D-Ind.) As "Mexico Joe" – an indication of a family business that relies on Mexican labor – even when it comes to health care, business or economics the Iranian nuclear contract goes.
In Missouri, Republican candidate Josh Hawley has called the caravan to force Democratic Senator Claire McCaskill unwillingly to enforce border controls.
"This is the kind of weakness that invites this mess, it really invites this national security crisis," he said in Fox News. "We can not afford that."
Sen. Ted Cruz (R-Tex.) Went one step further and made fun of the fact that his democratic opponent wants to lead the caravan.
"There is a caravan heading north," Cruz told fans on Saturday. "I'm just waiting for Beto O'Rourke to come down and lead the caravan."
O Rourke condemned this kind of "paranoia and fear" on Wednesday and said it was circulated shortly before the election "A government that wants to scare us."
"Do you want to be motivated by fear, paranoia – or are we the big, brave, self-confident country we know each other in?" He said.
In some blue and purple states, Democrats have used the president's focus on the caravan to go into offense. On Tuesday evening, during the final debate in Colorado's run for Governor, Democratic candidate Jared Polis took a question about the caravan as an opportunity to focus on the unpopular policies of the Trump administration to separate immigrant families at the border.
National emergency, and it's an emergency of character, "said Polis, a Boulder Congressman who voted against the separation policy." It's an emergency when a two-year-old kid is ripped from his mother's arms and thousands of miles away is sent away. It's not like who we are as a nation. "
Republican candidate Walker Stapleton asked if the caravan members in Colorado were" welcome "and said they would not, but said he would not send the National Guard to the border if that would be the separation Families meant and he signaled that he supported legal status for young immigrants who were brought to the United States by their parents.
"We lived in the state of Colorado with the failure of the federal government to solve our immigration problems, "said Stapleton," I do not support family separation. I support "Dreamer". I support those who contribute to the structure of our state. "
Frank Luntz, a Republican pollster who has led numerous focus groups with voters, said that both parties misunderstand the nation's feelings: Democrats underestimate the public's desire for more border security, while Republicans express their empathy for immigrants and their plight
"I think the Republicans made a mistake by not focusing on the economy," Luntz said. "It may not be that hot, but it does have a bigger impact on people's daily lives , I think that any distraction from the economic success of the past two years is not good for the Republicans. And that includes immigration, and that includes the caravan.
David Weigel and Scott Clement contributed to this report.