Senate Judiciary Chairman Charles E. Grassley claimed, citing “Law Enforcement Sensitive” information, that his office has received information that among the thousands of Central American immigrants in a caravan headed for the United States are a child molester and members of the violent MS-13 gang.

Grassley wrote a letter Thursday requesting briefings in front of the Judiciary Committee from Secretary of State Mike Pompeo and Homeland Security Secretary Kirstjen Nielsen on “the makeup of the caravan,” including any “national security threats” among its travelers.

“According to information obtained by my office,” Grassley added, “several members of the first caravan have significant criminal histories, including assault and sexual misconduct against a child, and membership in the MS-13 gang.”

A spokesman for Grassley’s office said it received “Law Enforcement Sensitive” information that prompted the briefing request. “The letter references that information to the extent it can be described while also respecting its sensitivity,” the spokesman said.

Law Enforcement Sensitive information is typically characterized as unclassified information that, if disclosed, could hamper or endanger law enforcement investigations, operations, or personnel.

Eager to keep his conservative base fired up just days before midterm elections that will shape his domestic agenda, President Donald Trump on Wednesday claimed the caravan headed to the U.S.-Mexico border includes “very tough fighters” that had wounded Mexican security personnel as they crossed the border from Guatemala.

Reports on the ground from Mexico, where two migrant groups have been moving toward the border, mostly have described rock-throwing members of the caravans, or the throng using its numbers and mass to climb over fences or overwhelm outnumbered Mexican security forces.

But the U.S. commander in chief contended in a Wednesday morning tweet that the caravans, one with young people and the other composed mostly of women and children, “are made up of some very tough fighters and people.”

Trump has ordered thousands of U.S. military forces to the country’s southern border to support law enforcement entities in a show of force aimed at trying to convince the caravans to turn around. Democrats say the move is meant to rally his conservative base ahead of the midterm elections next Tuesday.

John Bennett contributed to this report.