One of Ms. Ortega’s lawyers, Domingo Garcia, said the case also raised questions about equality in the justice system. He cited a case three years ago in Fort Worth, in which a 16-year-old boy from a wealthy white family was sentenced to probation for a drunken-driving crash that killed four and seriously injured two. The boy’s lawyers argued that he was so spoiled that he did not realize that there were limits on his behavior, the now notorious “affluenza” defense.

Attorney General Ken Paxton, a Republican who brought the fraud charges, has applauded Ms. Ortega’s sentence, saying that it “shows how serious Texas is about keeping its elections secure.”

Ms. Ortega said she had voted for Mr. Paxton as well as Mitt Romney, President Barack Obama’s Republican rival in 2012, after being persuaded by the conservative father of her fiancé, Oscar Sherman.

The outlines of Ms. Ortega’s offense are mostly undisputed. While living in neighboring Dallas County, she registered to vote before the 2012 election, checking a box on the registration form that certified that she was a United States citizen. After voting in 2012 and 2014, she moved to Fort Worth’s Tarrant County in 2015, where she registered to vote again — this time, ticking the box that indicated she was not a citizen.

When her registration was rejected, she called elections officials, telling them that she had voted in Dallas. Told that people who checked the noncitizen box were ineligible to vote, she reapplied, this time indicating that she was a citizen. An elections worker who remembered her earlier comment about voting in Dallas became suspicious, and forwarded the application to the authorities.

Ms. Ortega was jailed on charges of voting fraud, a felony, and false statements on a registration application, a misdemeanor. State prosecutors argued that her actions and statements showed that she had intended to break the law, although they offered no explanation of why she would have sought to vote illegally.

A jury of 10 women and two men convicted her of the fraud charges, but the misdemeanor has yet to be adjudicated. After a month in jail, she was released on bail. Her four children have been placed with an ex-husband with whom she has scant contact.