U.S. Department of Homeland Security Secretary Markwayne Mullin said the probe into Ilhan Omar, a Somali-born Minnesota lawmaker, is a large case beyond just an individual.

“This isn’t just a case that’s targeting one individual. This is a large case that we have presented to the DOJ, and the DOJ is leading the investigations,” Mr Mullin told Fox News on Friday.

The DHS Secretary dismissed criticisms that the Trump administration is weaponising law enforcement agencies against a perceived political opponent.

“And I’ll just say this again: We’re enforcing our nation’s laws, and we’re going to do that. We’re not weaponising. We’re not using political theatre on this,” he said.

Ms Omar, 44, is under probe over allegations that she married her brother, Ahmed Elmi, to bring him into the U.S. and obtain the country’s citizenship.

The Somalia-born American lawmaker has dismissed the allegations as lies that emanated from a ragtag Somali blog, accusing Mr Trump of politically unleashing enforcement agencies against her.

“The full weight of the federal government is being brought down on a law-abiding elected official because she has dared to criticise the president,” former American President Barack Obama said in a post on X, describing Ms Omar’s probe as “so appalling”.

Democratic lawmakers have also opposed the investigation into Ms Omar’s alleged immigration fraud, accusing the Trump administration of weaponising federal law enforcement.

A letter dated October 26, written by Rep. Pramila Jayapal (D-Wash.) and signed by 175 House Democrats, accused the Justice Department and the Department of Homeland Security of weaponising law enforcement against Ms Omar.

However, fresh evidence shows Mr Obama’s administration started the probe into Ms Omar and her ex-husband’s immigration matter.