Photographs shared by local reporters showed agents at Cuellar’s residence in Laredo removing bags, bins, and at least one computer.
Federal agents also went to Cuellar’s campaign office.
In a statement to media outlets, the FBI said the bureau “was present in Laredo conducting court-authorized law enforcement activity.”
“The FBI cannot provide further comment on an ongoing investigation,” it said.
A Cuellar spokesperson told media outlets: “Congressman Cuellar will fully cooperate in any investigation. He is committed to ensuring that justice and the law are upheld.”
Cuellar, 66, has represented Texas’s 28th Congressional District since 2005. The district includes land that touches the U.S.–Mexico border.
Considered to be a moderate, he has been a frequent critic of Biden’s lax immigration enforcement policies, which experts say have contributed to the explosion in illegal immigration recorded since Biden took office one year ago.
Under the Democratic president, the most illegal immigrant apprehensions at the southwest border were recorded for both a fiscal year and a calendar year.
Shortly after being sworn into office, Biden halted construction of the border wall, curbed the use of pandemic-era expulsion powers, and directed officials to end the “Remain in Mexico” program, which forced many asylum-seekers to wait in Mexico for their claims to be heard.
Some of the administration’s moves have been blocked or reversed by courts, but December 2021 arrests were higher than the month before, according to preliminary figures provided in court documents by the Customs and Border Protection agency.
Attorney Jessica Cisneros and educator Tannya Benavides are challenging Cuellar in the Democratic primary for his seat.
Cueller beat Cisneros in the previous primary by about 2,700 votes.
Cisneros has targeted Cuellar’s reputation and voting record, calling him “Trump’s favorite Democrat” and criticizing his willingness to work with Republicans on legislation.
Benavides has offered a similar critique, saying the district should be represented by a more progressive Democrat.