METAPA, Mexico: Honduran migrants, heading in a caravan to the US, board a truck on their way to Tapachula in Mexico's Chiapas state yesterday. - AFP

WASHINGTON/TAPACHULA, Mexico: US President Donald Trump yesterday vowed to begin curtailing tens of millions of dollars in aid to three Central American nations and called a caravan of migrants bound for the United States a national emergency as he sought to boost his party's chances in Nov 6 congressional elections. "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," Trump wrote in a series of Twitter posts.

Trump and his fellow Republicans have sought to elevate the caravan, which has made its way into Mexico bound for the US border, and immigration as campaign issues ahead of the midterm elections, in which his party is fighting to maintain control of the US Senate and House of Representatives. "Remember the Midterms!" Trump wrote in Twitter posts decrying the caravan and attacking Democrats on immigration, as Republicans sought to energize their conservative political base.

Trump, who has taken a hard line toward illegal immigration since taking office last year, also wrote that he had alerted the US military and Border Patrol "that this is a National Emergy," though he did not say what actions he was planning. He also complained that Mexico's police and military "are unable to stop" the caravan.

UN spokesman Farhan Haq said it is estimated that the caravan includes more than 7,000 people, "many of whom intend to continue the march north" toward the United States. At least 5,000 migrants, mostly Honduran, massed late on Sunday in the Mexican city of Tapachula near the Guatemalan border, local police said. About another 1,000 migrants were walking toward them from Ciudad Hidalgo further south, according to a Reuters witness.

In campaigning for Republican candidates last week, Trump highlighted the caravan issue. Trump traveled to Texas, a key border state, later yesterday to campaign for Republican US Senator Ted Cruz, who is seeking re-election. Since Trump became president last year, the United States has already moved to sharply decrease aid to Central America. In 2016, the United States provided some $131.2 million in aid to Guatemala, $98.3 million to Honduras, and $67.9 million to El Salvador, according to US data. By next year, those sums were projected to fall to $69.4 million for Guatemala, $65.8 million for Honduras and $45.7 million for El Salvador. The cuts amount to a reduction of almost 40 percent for the three nations.

Trump was not specific about further aid cuts. Trump also said, without providing evidence, that "Criminals and unknown Middle Easterners" are mixed in with the caravan, a claim immigration advocates disputed. Haq said UN Secretary-General Antonio Guterres spoke with the presidents of Honduras and Guatemala over the weekend and that an "emergency team" of personnel representing the United Nations High Commissioner for Refugees (UNHCR) had been sent to southern Mexico.

Immigration advocacy groups said cutting US aid would be counterproductive to the goal of stemming a flow of migrants, noting that a key purpose of the assistance over the years has been to stabilize countries to make people less apt to leave. Writing in response to Trump on Twitter, Democratic US Representative Don Beyer said: "Trump and the Republicans have controlled the White House and Congress for the past two years. Anytime he whines about immigration, just remember that they have no real solutions."

Seeking to escape violence and poverty in their home countries, the migrants - men, women and children - have defied threats by Trump that he will close the US-Mexico border if they advanced, as well as warnings from the Mexican government. Most of the migrants were expected to stay in Tapachula through yesterday, according to Mexican police at the scene. Police in riot gear shadowed the caravan's arrival along a southern highway but did not impede the migrants' journey.

The caravan was still a long way - more than 1,800 km - from the US border. Long before it reaches the US border, Mexico hopes to disperse the convoy using bureaucratic procedures, telling migrants to register with authorities in order to submit applications for asylum in Mexico. That process can last weeks, and migrants are supposed to stay where they register while applications are processed. If they violate those rules, they face deportation.

Army Lieutenant Colonel Jamie Davis, a Pentagon spokesman, said that while National Guard troops are currently supporting the Department of Homeland Security 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. White House and Border Patrol representatives did not immediately reply to requests for comment. Congress has not fully funded Trump's proposed wall along the US-Mexican border, which he has argued is needed to combat illegal immigration.

"No one is going to stop us, after all we've gone through," said 21-year-old Aaron Juarez, who was accompanied by his wife and baby and was walking with difficulty because of an injury. Honduran farmer Edwin Geovanni Enamorado said he was forced to leave his country because of intimidation by racketeering gangs. "We are tired, but very happy, we are united and strong," he said. Britany Hernandez added: "We have sunburn. We have blisters. But we got here. Our strength is greater than Trump's threats."

Mexico's President-elect Andres Manuel Lopez Obrador called for fair treatment of the migrants. "We don't want them to face what (Mexicans) face when they need to look for work in the United States," he said on Twitter. Guatemalan President Jimmy Morales said more than 5,000 migrants had entered Guatemala from Honduras, but that some 2,000 had since returned home on a fleet of government-chartered buses. Morales and his Honduran counterpart Juan Orlando Hernandez said after meeting that the march was "violating the borders and the good faith of the states".

The Honduran president acknowledged that social problems were a contributory factor. "Without a doubt, we have a lot to do so that our people can have opportunities in their communities," he said. The migrants are generally fleeing poverty and insecurity in Honduras, where powerful street gangs rule their turf with brutal violence. With a homicide rate of 43 per 100,000 citizens, Honduras is one of the most violent countries in the world, according to a Honduran university study. - Agencies