What to Know
The caravan has snowballed since about 160 migrants departed Friday from the Honduran city of San Pedro Sula
On Tuesday, President Trump warned Central American countries they risk losing U.S. aid if they allow migrants illegal passage across border
The migrants are fleeing widespread poverty and gangland violence in one of the world's most murderous countries
More than 2,000 Honduran migrants traveling en masse through Guatemala resumed their journey toward the United States on Wednesday as U.S. President Donald Trump sought to turn the caravan into a political issue three weeks before midterm elections.
A day after warning Central American governments they risk losing U.S. aid if they don't do something and saying that anyone entering the U.S. illegally would be arrested and deported, Trump turned his sights on Democrats and urged Republican allies to campaign on border security.
"Hard to believe that with thousands of people from South of the Border, walking unimpeded toward our country in the form of large Caravans, that the Democrats won't approve legislation that will allow laws for the protection of our country. Great Midterm issue for Republicans!" Trump said in a Wednesday morning tweet.
"Republicans must make the horrendous, weak and outdated immigration laws, and the Border, a part of the Midterms!" he continued.
On Thursday, Trump said on Twitter he would close the southern border if Mexico doesn't act to stop the migrants from reaching the United States.
According to U.S. government documents obtained by NBC News, the caravan of migrants fleeing Honduras has grown from 2,000 to 4,000, and the Mexican government has sent an additional 500 federal police to its border with Guatemala in anticipation of the group's arrival.
The mass migration comes amid a reported surge in the number of people crossing illegally into the U.S. from Mexico, according to NBC News. In September, U.S. Border Patrol agents apprehended more than 41,400 people crossing the border illlegally, up from 37,544 in August, according to numbers not yet released publicly but obtained by NBC News.
In Guatemala, the migrants rose early and many left without eating breakfast, bound for Zacapa, the next city on their route. Overcast skies and a light drizzle took the edge off the sweltering heat and humidity, making the trek more bearable.
Luis Navarreto, a 32-year-old migrant in the caravan, said he had read about Trump's threats to his country but was undeterred.
"We are going to continue," Navarreto said. "It is God who decides here. We have no other option but to move ahead."
The migrants are fleeing widespread poverty and gangland violence in one of the world's most murderous countries, and many blame Honduran President Juan Orlando Hernandez for what they call unlivable conditions back home.
"We are here because of Juan Orlando," said Nelson Zavala, a 36-year-old laborer.
The previous day the migrants advanced about 30 miles (40 kilometers) from the Honduras-Guatemala border to arrive at the city of Chiquimula.
That is a tiny portion of the almost 1,350 miles (2,200 kilometers) they would have to travel to reach the closest U.S. border.
Some were able to hitch rides, packing the flatbeds of pickups and farm trucks, and even cargo holds of semis, while many more continued on foot with backpacks, strollers and Honduran flags. Hundreds advanced farther and faster than the main group to reach the Guatemalan capital, according to the Casa del Migrante shelter there.
The caravan has snowballed since about 160 migrants departed Friday from the Honduran city of San Pedro Sula, with many people joining spontaneously while carrying just a few belongings. Estimates of their numbers ranged up to 3,000.
Three weeks before the U.S. elections, the caravan was bound to draw Trump's ire. But he did not follow through on a similar threat to cut aid to Honduras in April over an earlier caravan, which eventually petered out in Mexico.
On Tuesday, Honduras' president accused unnamed "political groups" organizing the caravan based on lies in order to cause problems in Honduras.
"There are sectors that want to destabilize the country, but we will be decisive and we will not allow it," Hernandez told reporters.
Earlier the Foreign Ministry alleged that people had been lured to join the migration with "false promises" of a transit visa through Mexico and the opportunity to seek asylum in the United States.
In a joint statement Wednesday, Mexico's Foreign Relations and Interior departments said anyone in the caravan with travel documents and a proper visa will be allowed to enter, and anyone who wants to apply for refugee status can do so.
But the statement said all cases must be processed individually, suggesting that authorities have no intention of letting the migrants simply cross the border en masse without going through standard immigration procedures.
It warned that anyone who enters Mexico in an "irregular manner" faces detention and deportation.
None of the migrants The Associated Press spoke to on the road was carrying a passport. When agents in Guatemala near the Honduran border asked a crowd of them what documentation they were carrying, they held up national personal ID cards, which allow them to move through most countries in Central America — but not Mexico, which requires foreigners to present a passport for entry.
Late Tuesday, Trump said via Twitter that Washington had told Honduras, Guatemala and El Salvador that the U.S. will stop aid "if they allow their citizens, or others, to journey through their borders and up to the United States, with the intention of entering our country illegally."
Guatemalan President Jimmy Morales said Wednesday that he had spoken twice with U.S. President Mike Pence.
As for Guatemala's government, Morales said, "We do not accept conditions; we do not impose conditions. What we do is accept our responsibilities and we are going to prioritize what our laws say."
He added that he had also discussed with Honduras' Hernandez the facilitation of "the most comfortable, feasible and humane return possible for any who wish to go back."
Morales said that while Central Americans are legally free to transit from country to country, a "massive ingress of people without registering" puts Guatemala in a difficult position because it's impossible to know who the people are and what may be the intentions of any of their leaders.
Luis Arreaga, the U.S. ambassador to Guatemala, posted a video message on Twitter to migrants thinking of entering the United States illegally.
"If you try to enter the United States, you will be detained and deported," Arreaga said in Spanish. Addressing those already en route, he added: "Return to your country. Your attempt to migrate will fail."
Also Wednesday, some 300 Hondurans arrived at the El Salvador border hoping to make it to join the caravan in Guatemala.
A Salvadoran government statement and the country's migration director, Herbert Hernandez, said about 100 of the Hondurans tried to enter "without going through the obligatory migration control" and soldiers and police took control of a border bridge between the two countries.
Some from the group went through the standard migration processing and were allowed to enter El Salvador. Others who refused were partially impeding the crossing.
"Transit at the El Amatillo border is blocked by these people, not by ... the government," Hernandez said.
Associated Press writers Marcos Aleman in San Salvador, El Salvador, and Peter Orsi in Mexico City contributed to this report.