AUSTIN, Texas (AP) — Rep. Henry Cuellar of Texas, one of the only anti-abortion Democrats remaining in Congress, faced the toughest reelection fight of his career Tuesday in a primary runoff against progressive Jessica Cisneros that could offer clues over how much abortion rights could animate voters in the 2022 midterms.

By late Tuesday, the race was neck-and-neck, with the two repeatedly swapping leads. The winner will face Cassy Garcia, who won the Republican runoff for the seat.

Cuellar has come under increased attacks from abortion rights groups over his position in the weeks since a leaked U.S. Supreme Court opinion draft showed the justices are poised to overturn a constitutional right to abortion, which has been in place for 50 years. It would then be up to the states to regulate abortion, unless Congress codifies into law the right to abortion access.

In March, Cisneros, a 28-year-old immigration attorney, forced the runoff after she came within 1,000 votes of Cuellar, a nine-term incumbent, in the primarily Hispanic district with a large Catholic population. Cuellar has received support from fellow Democrats in Congress, including U.S. House Speaker Nancy Pelosi.

"It is our fundamental freedoms on the line," Cisneros told reporters last week. "I am more than happy to do what we can to make sure we are delivering on the promises Democrats successfully ran on in 2020."

In the closing weeks, abortion rights groups poured money and resources on the ground and across TV in South Texas, where Cuellar has been in office for 17 years and beat Cisneros in the primary two years ago. Progressive leaders including Rep. Alexandria Ocasio-Cortez, of New York, and Sen. Bernie Sanders, of Vermont, have also come to Texas to campaign with Cisneros.

That has made the runoff another test of whether progressives can topple other moderate, establishment-oriented candidates. Cuellar's unapologetic defense of gun rights and support of the oil and gas industry, which is a major employer in his district that runs from San Antonio to the border with Mexico, are also out of step with many Democrats. The runoff came the same day that an 18-year-old gunman killed at least 19 children at an elementary school in a district neighboring Cuellar's.

Cuellar came under scrutiny in January after FBI agents searched his house in the border city of Laredo as part of an investigation related to the former Soviet Republic of Azerbaijan. His lawyer said last month that federal authorities informed him that Cuellar was not the target of the investigation. The FBI and a spokesman for the U.S. attorney's office in Washington had declined to comment.

Ocasio-Cortez slammed the House Democratic leadership for supporting Cuellar in the race.

"On the day of a mass shooting and weeks after news of Roe, Democratic Party leadership rallied for a pro-NRA, anti-choice incumbent under investigation in a close primary. Robocalls, fundraisers, all of it," Ocasio-Cortez tweeted late Tuesday. "Accountability isn't partisan. This was an utter failure of leadership."

But Texas Republican Sen. John Cornyn said Cuellar has a better pulse on South Texas, where the GOP is taking a bigger swing in 2022 after decades of writing off the region as a Democratic stronghold.

The new optimism by Republicans along Texas' border with Mexico comes after several counties showed a dramatic increase in support for GOP candidates in 2020.

"What the progressives in Washington, D.C., don't understand is that much of our Hispanic population in South Texas is pretty conservative, sort of from a cultural standpoint," Cornyn said last week. "And I think Henry fits that district and that temperament and that attitude very well."

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