Anthony James Kazmierczak, 55, pleaded guilty in U.S. District Court to one count of assaulting a United States officer in connection with the Jan. 27 incident, in which prosecutors said he sprayed Omar with apple cider vinegar from a syringe during a public event focused on immigration enforcement policies.

The Justice Department said Kazmierczak acknowledged during a hearing before U.S. District Judge Joan Ericksen that he had planned the assault in advance and acted because he disagreed with Omar’s positions on immigration and federal enforcement actions.

The attack occurred as Omar criticized the U.S. Immigration and Customs Enforcement agency’s operations in Minnesota and discussed fatal shootings involving federal agents in Minneapolis. Authorities said the liquid sprayed on Omar’s clothing and skin was later confirmed through laboratory analysis to contain acetic acid.

Omar was not injured.Security personnel subdued Kazmierczak after he shouted and gestured toward Omar during the event, according to officials. He was later arrested, while the town hall resumed after a temporary disruption.Omar, a Somali-born Muslim lawmaker who arrived in the United States as a refugee child and became a U.S. citizen in 2000, has frequently been the target of political attacks and threats linked to her outspoken criticism of Republican immigration policies and U.S. foreign policy.

President Donald Trump has repeatedly criticized Omar publicly and on social media, including remarks questioning her place in the United States and calling for punitive action against her. Civil rights advocates and political analysts have warned that increasingly hostile rhetoric directed at elected officials has contributed to a broader rise in political intimidation and violence across the country.

The Justice Department did not immediately disclose a sentencing date. Federal assault charges involving attacks on elected officials can carry prison terms and financial penalties depending on the severity of the offense and intent established by prosecutors.