Democratic presidential candidate Joe Biden is backing Eliz Markowitz in the special election runoff for state House District 28, her highest-profile endorsement yet in the battleground race.

Markowitz faces Republican businessman Gary Gates in the Jan. 28 race to replace former Rep. John Zerwas, R-Richmond. Democrats are working to flip the suburban Houston seat as they look to capture the House majority in November.

Biden cited Markowitz's extensive education background in endorsing her. Markowitz, who ran unsuccessfully last year for the State Board of Education, is a longtime instructor, trainer and author with The Princeton Review.

"I’m from a family of teachers and I know the real deal: Not only is Eliz an educator and activist — she’s the kind of fighter who will bring heart and smarts to the statehouse and to communities across Texas and at home in Fort Bend County," Biden said in a statement. "She has worked to boost access to health care and quality public education, and to train other teachers across the country. Let's help her continue that fight for our families and futures on January 28th."

Biden, who is leading Texas presidential primary polls, is the latest White House contender to get involved in the runoff after Michael Bloomberg visited the district late last month to stump with Markowitz. The ex-New York City mayor did so at the recommendation of Beto O'Rourke, the former El Paso congressman who has taken a close interest in the race, especially since ending his presidential bid in November. O'Rourke first campaigned with Markowitz in September and is set to return to the district this weekend for his third trip there to help her.

Early voting begins Jan. 21 for the runoff.