President Donald Trump says "full efforts" are being made to stop the caravan of Honduran migrants currently in Mexico from crossing into the U.S.
"People have to apply for asylum in Mexico first and if they fail to do that, the U.S. will turn them away," Trump tweeted, adding that "courts are asking the U.S. to do things that are not doable!"
"The Caravans are a disgrace to the Democrat Party. Change the immigration laws NOW!" he demanded.
Trump and the Republicans have made immigration a major issue in next month's congressional elections. They accuse Democrats of favoring open borders that let criminals and drugs flow into the U.S.
The caravan of close to 3,000 people left San Pedro Sula, Honduras last week, made its way through Guatemala, and were held up at the Mexican border Saturday.
Mexican authorities refused to let the migrants enter in masse, saying only those with passports or visas could come through. Small groups of others were given temporary residency permits so they could apply for asylum.
"We will offer jobs, work to Central Americans. Anyone who wants to work in our country will have help, will have a work visa," Mexican President-elect Andres Manuel Lopez Obrador said last week.
While some of the migrants boarded busses to return home, most became impatient waiting at the border and crossed the muddy river into Mexico by foot or on small boats provided by local residents.
Mexican police and authorities made no move to stop them.
Observers say the caravan has swelled to about 5,000 and Trump's harsh words and threats to deploy the U.S, military along the southern border have not deterred them.
"No one will stop us, only God," a Honduran man told the Associated Press.
Others walked while holding the hands of children clutching dolls and stuffed animals. They say their kids are the reason they are making the dangerous journey.
Honduras is one of the most violent and deadliest nations on earth, in part, because of gangs and drugs.
Many of those trying to get to the United States want to escape the daily threat to their lives, the lack of good jobs, and want to get their children away from the influence of gangs.
The U.S. Department of Homeland Security is monitoring the caravan. It warns of the threat of criminal activity against those traveling through Mexico.
"While we closely monitor the caravan crisis, we must remain mindful of the transnational criminal organizations and other criminals that prey on the vulnerabilities of those undertaking the irregular migration journey," Homeland Security Secretary Kirstjen Nielsen said in a statement Sunday, adding that the U.S. will work with partners in the region "to investigate and prosecute to the fullest extent of the law all who seek to encourage and profit from irregular migration."
The Red Cross said Saturday that many of the people they are supporting, a majority of who are women and children, are suffering from dehydration, stomach infections, and foot injuries as they walk the long journey."
Walter Cotte, International Federation of Red Cross and Red Crescent Societies regional director for the Americas, said in a statement: "It is imperative that the dignity and security of families are safeguarded and they are kept together."