A caravan of approximately 7,000 refugees and migrants is around a thousand miles away from the US-Mexico border, but the migrants' presence is felt almost everywhere on the campaign trail just a few weeks ahead of the 2018 midterms.

Most of the people are fleeing rampant poverty and gang violence in Guatemala, Honduras, and El Salvador as they travel by foot, truck, and river to search for work or asylum in Mexico or the US.

They appear to be undeterred at the prospect of family separation or detention which is part of Donald Trump's "zero tolerance" stance on immigration, but their journey is a central issue in several midterm election campaigns from Texas, Arizona, California, and during any of the many "Make America Great Again" political rallies Mr Trump has held recently.

Here are four things you should know about the group:

Trump has alerted the US military

“Sadly, it looks like Mexico’s Police and Military are unable to stop the Caravan heading to the Southern Border,” Mr Trump tweeted after Mexican riot police failed to contain thousands of people from crossing into the country at its own southern border with Guatemala.

The caravan, mostly Hondurans, crowded into the Mexican border city of Tapachula over the weekend after trekking on foot over the Suchiate River which separates the two countries.

“I have alerted Border Patrol and Military that this is a National Emergy [sic]. Must change laws!” Mr Trump said. “Guatemala, Honduras and El Salvador were not able to do the job of stopping people from leaving their country and coming illegally to the US. We will now begin cutting off, or substantially reducing, the massive foreign aid routinely given to them.

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“Criminals and unknown Middle Easterners are mixed in,” the president wrote, although no evidence has been provided for either claim. Mr Trump has repeatedly called the thousands on the Mexico border “criminals”.

It is unclear what military action would entail at the US-Mexico border but Lieutenant Colonel Jamie Davis, a Pentagon spokesman, said that while National Guard troops are currently supporting the Department of Homeland Security (DHS) on the border, the Pentagon had not been asked to provide additional support.

There are currently 2,100 National Guard troops along the border in Texas, New Mexico, Arizona and California, according to the Pentagon.

Republicans are using it as a campaign line ahead of the midterms

Mr Trump has repeatedly called for immigration law reform in light of the influx of undocumented immigrants fleeing rampant gang violence and poverty in Honduras, Guatemala, and El Salvador. He has made the issue – and his hardline stance – central to the upcoming midterm elections in Congress.

He has been speaking about the issue of immigration at dozens of political rallies across the country ahead of the 6 November midterm elections. He also held another “Make America Great Again” rally in Texas earlier in the week.

“Every time you see a Caravan, or people illegally coming, or attempting to come, into our Country illegally, think of and blame the Democrats for not giving us the votes to change our pathetic Immigration Laws!,” Mr Trump said, as a reminder his supporter base in a series of tweets to begin the week.

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Republicans running for office in Texas, New Mexico, and Arizona have mimicked the ‘politics of fear’ rhetoric as well, painting the migrants as members of the violent MS-13 gang coming to hurt Americans.

An online anti-immigrant advertisement tracker shows the number of messages not just targeted to incite xenophobia among voters but aimed at painting Democrat opponents as allowing “criminals” into the US with open border policies.

One ad, paid for by the National Republican Congressional Commission and in support of candidate Lea Marquez Peterson, shows a white American woman locking all her doors and windows in fear of undocumented immigrants and paints opponent Democrat Ann Kirkpatrick as not having that voting bloc’s safety in mind.

The ad is titled “Forgotten”.

Texas Senator Ted Cruz’s re-election campaign has run an ad painting opponent Democrat Beto O’Rourke as being weak on criminalising illegal entry into the US but also shows a series of undocumented immigrants who were deported multiple times and convicted of felonies like sexual assault.

Conditions these refugees and migrants are fleeing in their home countries

As media use the terms “flood,” “deluge” and “army” of migrants to describe the massive movement of people towards the US, voters may not understand the conditions the migrants are fleeing.

Gang violence related to narcotics is rampant in that part of Central America and particularly in Honduras where the Mara Salvatrucha (MS-13) and Barrio 18 gangs rule among a host of others.

As National Geographic reported: “It’s in places like this where generations of young people have realised that in Honduras the self-perpetuating cycles of violence, corruption, and poverty have robbed them of their right to grow old.”

The gang violence is in a vicious cycle with rampant poverty from an economy dependent on a flailing agricultural system, malnutrition, lack of work opportunities for the non-wealthy classes, and poor public services in education and allocation of public funds.

Undocumented immigration across the US-Mexico border Show all 14 1 /14 Undocumented immigration across the US-Mexico border Undocumented immigration across the US-Mexico border Immigrant children, many of whom are separated form their parents, are housed in Texas' tent city Reuters Undocumented immigration across the US-Mexico border A two-year-old Honduran asylum seeker cries as her mother is searched and detained near the US-Mexico border Getty Undocumented immigration across the US-Mexico border Undocumented migrants ride on the top of a freight train referred to as the beast, or La Bestia Getty Undocumented immigration across the US-Mexico border A cage inside a US Customs and Border Protection detention facility in Texas Reuters Undocumented immigration across the US-Mexico border US Border Patrol Academy All new agents must complete a months-long training course at the New Mexico facility before assuming their posts at Border Patrol stations, mostly along the US-Mexico border Getty Undocumented immigration across the US-Mexico border US-Mexico border fence A group of young men walk along the Mexican side of the US-Mexico border fence in a remote area of the Sonoran Desert Getty Undocumented immigration across the US-Mexico border US-Mexico border fence in the US Man looks through US-Mexico border fence into the US in Tijuana, Mexico Getty Undocumented immigration across the US-Mexico border US-Mexico border fence US Border Patrol agent Sal De Leon stands near a section of the US-Mexico border fence while stopping on patrol on in La Joya, Texas Getty Undocumented immigration across the US-Mexico border US Border Patrol Academy US Border Patrol instructor yells at trainees after their initial arrival to the academy Getty Undocumented immigration across the US-Mexico border Memorial service in Guatemala Families attend a memorial service for two boys who were kidnapped and killed in San Juan Sacatepequez, Guatemala. Crime drives emigration from Guatemala to the United States, as families seek refuge from the danger Getty Undocumented immigration across the US-Mexico border Arrests on the border Undocumented immigrants comfort each other after being caught by Border Patrol agents near the US-Mexico border Getty Undocumented immigration across the US-Mexico border Detention holding facility A boy from Honduras watches a movie at a detention facility run by the US Border Patrol Getty Undocumented immigration across the US-Mexico border Mexican farm workers Mexican migrant workers harvest organic parsley at Grant Family Farms in Wellington, Colorado Getty Undocumented immigration across the US-Mexico border Mexican family in Arizona A Mexican immigrant family sits in the living room of their rented home in Tuscon, Arizona. The family that Arizona's new tough immigrant law had created a climate of fear in the immigrant community. Getty

There is no indication this particular group of migrants is armed in any way. Many are parents travelling with children and the barest of necessities - a bit of food, water, and often just a few pieces of clothing - to survive the thousands of miles needed to go before reaching the border.

Many of the approximately 7,000 migrants will also likely not make the full journey to the McAllen, Texas, or Tijuana, Mexico, entry points either.

After around 1,500 migrants were seen travelling through Mexico last year, only a few hundred made it to the border crossing where - this past summer - they faced Mr Trump’s “zero tolerance” and family separation policies.

Asylum is not actually a crime

For the migrants who do make it to the border - likely only a small percentage of the 7,000 in this particular group - many will probably attempt to seek asylum.

Per US Citizenship and Immigration Services, asylum seekers must "demonstrate [they] have suffered persecution or fear that they will suffer persecution due to" five factors: race, religion, nationality, membership in a particular social group, or political opinion.

The majority of migrants in the caravan are fleeing some of the world's most violent areas in terms of gang violence, murders per capita, and drug cartel control.

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They have up to one year to apply for the status after they arrive in the US. The process can take up to 180 days and involves being fingerprinted and government officers running a check on all the claims being made in the application.

It is not a crime to enter the country without documentation if that person declares they are seeking the protected status.

During the administration of Barack Obama, undocumented immigrants would be detained initially but then released pending a court hearing to begin the process of granting asylum.

However, Attorney General Jeff Sessions has instituted a policy which essentially makes it a violation requiring detention.

It was what led to more than 2,000 children being taken away from families at the border as parents were jailed immediately and children cannot enter the US criminal justice system.

Instead, they were housed in separate ‘tent cities’ and centres along the border but also as far away as Chicago and New York.