President Trump risks violating federal law in his effort to cut aid to a trio of Central American countries, according to a senior House Democrat.

Trump announced a desire to “begin cutting off” foreign aid to El Salvador, Guatemala, and Honduras as punishment for a flow migrants from those countries headed toward the United States. New York Rep. Eliot Engel, the top Democrat on the House Foreign Affairs Committee, countered that Trump lacks the authority to make those decisions unilaterally due to a law called the Impoundment Control Act.

“Fortunately, Congress — not the president — has the power of the purse, and my colleagues and I will not stand idly by as this administration ignores congressional intent,” Engel said Monday.

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About 5,000 people are trying to travel from Central America to the United States. Secretary of State Mike Pompeo announced an agreement last week with the Mexican government to work with the United Nations to review asylum requests on the southern border of Mexico, but the migrants reportedly intend to continue north.

“We are concerned that these migrants may be victimized by human smugglers or others who would exploit them,” Pompeo said late Sunday. “We also are deeply concerned by the violence provoked by some members of the group, as well as the apparent political motivation of some organizers of the caravan.”

Trump said “unknown Middle Easterners are mixed in” with the caravan, but Associated Press reporters embedded with the group have not met anyone from that region.

“There isn’t a single terrorist here,” Denis Omar Contreras, one of the leaders of the People Without Borders group organizing the trek, told the AP. “We are all people from Honduras, El Salvador, Guatemala, and Nicaragua. And as far as I know, there are no terrorists in these four countries, at least beyond the corrupt governments.”

Engel argued that cutting American aid to those countries would only exacerbate the problems that inspire people to leave for the United States.

“El Salvador, Honduras, and Guatemala are plagued by violence and poverty,” he said. “The best way to keep Central Americans from migrating to the United States is to continue investing in their communities so that they are not forced to make the dangerous trek north. Yet again, President Trump’s policy toward Latin America will only make things worse.”