Former President Barack Obama has condemned a federal investigation into congresswoman Ilhan Omar as "so appalling," saying she is being targeted solely for criticizing President Donald Trump.

"The full weight of the federal government is being brought down on a law-abiding elected official because she has dared to criticize the president," Obama wrote on X on Sunday. He called the probe an example of potential future political abuse, warning that if it becomes "the new normal, there's no reason to believe it will stop with her."

Last week, Department of Homeland Security agents searched Omar's Washington DC home as part of an investigation into her citizenship and immigration status. The Minnesota Democrat was born in Somalia and moved to the United States as a child. US media outlets have reported the probe concerns whether she lied about her age when arriving in the US in 1995, and whether the age listed on her citizenship application differs from her actual birth date.

According to US Citizenship and Immigration Services law, a child born outside the US automatically becomes a citizen when a parent becomes a citizen by naturalization, provided the child is under 18 and a lawful permanent resident in that parent's custody. Obama stated Omar's father became a naturalized citizen when she was 17, which would have granted her citizenship.

"Now the Administration is actively trying to deport Congresswoman Omar, seemingly based solely on the unsubstantiated theory that she was actually 18 when her father was naturalized," Obama wrote.

The White House defended the investigation. Spokeswoman Lauren Bis said the Justice Department is "focused on restoring law and order and keeping Americans safe" and denied the probe was politically motivated. Trump said the investigation had "nothing to do" with him, though he called Omar a "terrible person" and "complainer."

Federal agents seized Omar's phone, computers, notebooks and passport. Her lawyers have demanded their return, arguing the seizure violated judicial protections for her work as a federal lawmaker and that agents failed to properly notify her or allow her to contact counsel immediately.

Omar characterized the investigation as "the latest escalation in his campaign of political intimidation," citing what she calls years of Trump targeting her with "baseless lies and smear campaigns."

Democrats have characterized the raid as presidential interference with the legislative branch. Republicans say Omar should face the same legal treatment as anyone else.