The punishment was strikingly harsh for an offense that usually merits far less jail time, if any. A second fraudulent ballot case in metropolitan Fort Worth ended in 2015 with probation.
Ms. Ortega insisted in court that she had been unaware that she was ineligible to vote and was confused by registration forms and explanations by election officials.
Prosecutors for Mr. Paxton and Tarrant County said that she had lied and that the same forms and conversations proved it. A jury convicted her Wednesday of two felony charges.
Mr. Birdsall said that Mr. Paxton’s office had been prepared to dismiss all charges against Ms. Ortega if she agreed to testify on voting procedures before the Texas Legislature. But the Tarrant County criminal district attorney, Sharen Wilson, vetoed that deal, he said, insisting on a trial that would showcase her office’s efforts to crack down on election fraud.
Both the attorney general’s office and the county prosecutor declined to comment on the specifics of Mr. Birdsall’s statement, citing privacy rules for plea-bargain negotiations. A spokeswoman for Ms. Wilson, Sam Jordan, said any negotiations were only “discussions,” a description Mr. Birdsall disputed.
Ms. Ortega’s conviction looks to be an early volley in a reinvigorated partisan war over voting rights — a war led in Texas by Mr. Paxton, who has crusaded against voter fraud. (Coincidentally, he faces legal issues of his own: state securities fraud charges and a federal lawsuit stemming from efforts to recruit investors for a technology company; he has denied wrongdoing).
Last year, federal courts curbed or nullified Republican-backed laws making it harder to vote, saying they reduced turnout by Democratic-leaning minorities, deliberately or otherwise.
Texas’s strict voter-ID law was among them. A federal appeals court ruled last year that the law hurt Latinos and African-Americans, who were less likely to have the IDs. It later ordered state officials to change their public education campaign on new ID rules.
With Mr. Trump’s election, a new Justice Department and a new conservative nominee to the Supreme Court, Republicans have renewed their push for strict voting requirements in the name of combating fraud. Experts widely dismiss the fraud claims as unfounded. In unguarded moments, a number of Republican politicians have acknowledged as much.
Ms. Ortega’s case is unusual not just for its harshness but for its circumstances. Many fraud convictions that draw prison sentences — and some that do not — involve clear efforts to influence election results. Texas prosecutors won prison sentences for four men who moved into a hotel in 2010 to claim residency so they could sway a local election. A woman in Brownsville, Tex., was placed on five years’ probation for casting five absentee ballots under different names in elections in 2012.
Lawyers offered no clear motive for Ms. Ortega’s decision to cast ballots beyond her desire to participate in elections.
Ms. Ortega, a native of Monterrey, Mexico, came to Texas with her mother when she was an infant. More than a decade later, the family was scattered after the mother was arrested and deported. Two brothers born in Dallas automatically gained citizenship; Ms. Ortega became a permanent resident and gained a green card, her brother Tony Ortega, 35, said in an interview.
As a Dallas County resident, she registered to vote and later cast ballots in elections in 2012 and 2014, her lawyer, Mr. Birdsall, said. While that was illegal, there was no attempt to break the law, he maintained: Some government forms allow applicants to declare that they are permanent residents, but the voting registration form asks only whether an applicant is a citizen.
Lacking the permanent resident option, he said, she ticked the “citizen” box. When the county later mailed her a registration card, he said, she believed she “was good to go.”
Ms. Ortega moved to neighboring Tarrant County and again registered, but this time checked a box affirming that she was not a citizen. When her application was rejected in March 2015, the trial showed, she called election officials and told them that she had previously voted in Dallas County without difficulty.
Told that she could not vote unless she was a citizen, she asked for another application, and returned it with a check in the box affirming citizenship. That raised questions, and law-enforcement officials arrested her on fraud charges.
Jonathan White, an assistant attorney general who helped prosecute the Ortega case with Tarrant County officials, said the evidence of fraud was unambiguous. “She told the elections office she was a citizen,” he said. “She told everyone else she wasn’t,” including a recorded statement to prosecutors in which she said she was a citizen of Mexico.
Mr. Birdsall said the arrest and prosecution are punishing a woman for her own confusion over whether residency and citizenship confer the same rights.
“She wasn’t trying to topple the country,” he said. “She was trying to make more serious decisions about our country than the 50 percent of the people who didn’t bother to vote in the last election.
“This country is so inflamed by this Donald Trump nonsense that they’ve turned her into a whipping boy,” he said.
Ms. Ortega is now in a Fort Worth jail awaiting transfer to a state prison. Her four children, ages 13 to 16, are being cared for by siblings and her fiancé, Oscar Sherman, 27, a trucker who said her arrest had scotched their plans to marry. The children’s fate is unclear. Mr. Sherman lacks legal custody; her siblings are still debating their options.
Ms. Ortega’s future is bleak. The federal government frowns on giving green cards to felons. “She’ll do eight years in a Texas prison,” Mr. Birdsall said. “And then she’ll be deported, and wake up blinking and scratching in a country she doesn’t know.”
Far-right websites have seized on Ms. Ortega’s conviction as proof that Mr. Trump is right about rampant fraud and efforts by Democrats to steal the November election.
There is, however, at least one flaw in that story: Ms. Ortega was a registered Republican.
“She voted for Mitt Romney over Barack Obama in the 2012 election. In 2014 she voted for our current attorney general, Ken Paxton,” Mr. Birdsall said. “And guess what? He’s the one responsible for prosecuting her.”
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