The man charged with squirting vinegar onto Representative Ilhan Omar at an event in Minneapolis this year was sentenced on Thursday to 14 months in prison following a plea deal with federal prosecutors, court records show.

The attack happened in January at a town-hall meeting where Ms. Omar had been calling for the resignation of Kristi Noem, then the homeland security secretary, at the height of the Trump administration’s immigration crackdown in the state.

Prosecutors say the man, Anthony J. Kazmierczak, 56, approached Ms. Omar while she was speaking and sprayed her with apple cider vinegar and water through a syringe. Ms. Omar’s security guards promptly tackled him. Ms. Omar was not hurt.

Mr. Kazmierczak, a Minneapolis resident, pleaded guilty in May to a federal charge of assault. His defense lawyers had asked for him to be sentenced to eight months. He was sentenced on Thursday to 14 months in prison and two years of supervised release, according to court records.

Federal prosecutors, in their sentencing memorandum, called the attack a “serious” offense in an era of growing political violence.

“It was not what we asked for, but it was not out of line either,” Mr. Kazmierczak’s lawyer, John Fossum, said of the sentence.

Mr. Kazmierczak had posted for years about his anger toward Democrats and had shown his support on social media for President Trump and other conservative figures. Before the town hall in January, Mr. Kazmierczak told a neighbor that he might be arrested at an event featuring Ms. Omar.

Ms. Omar, a progressive Democrat, was first elected to represent Minneapolis in 2018. She has been targeted by Mr. Trump for years. He has said that she should “go back” to her native country, Somalia, and has referred to her as “garbage.”

Shortly before Mr. Kazmierczak lunged at Ms. Omar with a syringe, Mr. Trump singled her out at a rally in Iowa, saying that foreigners coming into the United States “have to show they can love our country; they have to be proud — not like Ilhan Omar.”

In a statement on Thursday, Ms. Omar said that she was “grateful to the prosecutors and judge for holding the perpetrator accountable for his actions in January, adding that “political violence or threats are never acceptable.”

Mr. Kazmierczak still faces separate charges in state court. Hennepin County prosecutors charged him with one felony count of making violent threats and a misdemeanor assault charge.

Daniel Borgertpoepping, a spokesman for the office, said prosecutors were weighing whether to proceed with the state case.

“Our office will review Mr. Kazmierczak’s federal case and plea, communicate with the victims and decide on an appropriate path forward,” he said.