Twenty people in Florida have been charged with voter fraud, state officials said on Thursday. As of Thursday afternoon, 12 of the 20 people charged had been arrested, state officials said at a news conference in Lake Worth Beach, Fla. Most cases involved noncitizens who registered to vote, attesting that they were U.S. citizens, the officials said.

In announcing the arrests, Gov. Ron De Santis, a Republican, suggested that his state had done more to ensure the integrity of elections than Democratic-led ones such as California ahead of the midterms. Mr. De Santis made election security a priority after President Trump lost to Joseph R. Biden Jr., in 2020; Mr. Trump has fumed about the loss ever since, falsely claiming that the result was rigged.

Earlier this year, Mr. De Santis signed into a law requiring people show proof of U.S. citizenship when they registered to vote. At the news conference, officials highlighted the case of Cyntia Canales, of Ocala, Fla., who was arrested earlier this month by state agents. She is a legal U.S. resident originally from Chile.

Her defense lawyer blamed Ms. Canales’s unfamiliarity with the election system. Ms. Canales, 62, who is not a citizen, registered to vote in Florida in 2012. “She had voted all this time and it was never an issue,” the lawyer, Julia Slaughter, said. “She was shocked she was charged.”