Riley Gaines, a 12-time All-American swimmer who competed at Kentucky, blasted ESPN for honoring Lia Thomas in its "Celebrating Women’s History Month" segment.

Gaines has been at the forefront of women’s sports calling for fair treatment and keeping transgender women from competing against biological females at the highest level of competition. Gaines tied with the former Penn swimmer at the NCAA championships last year. Thomas’ performance in the pool caused a national firestorm.

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A photo illustration of Lia Thomas and Riley Gaines

University of Pennsylvania swimmer Lia Thomas and Kentucky swimmer Riley Gaines react after finishing tied for fifth in the 200 freestyle finals at the NCAA Swimming and Diving Championships on March 18, 2022, in Atlanta. (Rich von Biberstein/Icon Sportswire via Getty Images)

"Lia Thomas is not a brave, courageous woman who EARNED a national title," Gaines tweeted Sunday. "He is an arrogant, cheat who STOLE a national title from a hardworking, deserving woman. The @ncaa is responsible.

"If I was a woman working at ESPN, I would walk out. You're spineless @espn."

ESPN didn't immediately respond to Fox News Digital's request for comment.

The segment brought up Thomas’ transition from male to female, her win at the NCAA Championships and competing amid criticism from the swimming world.

Lia Thomas at the NCAA Championships

Lia Thomas after winning the 500-yard freestyle during the NCAA Division I Women's Swimming and Diving Championship at the McAuley Aquatic Center on March 17, 2022, in Atlanta. (Mike Comer/NCAA Photos via Getty Images)

ESPN HONORS LIA THOMAS IN 'CELEBRATING WOMEN’S HISTORY MONTH' SEGMENT

"People will say, ‘Oh, she just transitioned so she would have an advantage so she could win.’ I transitioned to be happy," Thomas says in the segment.

Thomas’ participation in NCAA women’s swimming during the 2021-22 season sparked a growing debate over the fairness of transgender women competing against biological females. She became the first transgender woman to win an Ivy League Championship and later an NCAA Championship in the 500 free.

Lia Thomas smiling in the pool following 100-yard freestyl

Pennsylvania's Lia Thomas smiles after winning the 100-yard freestyle final at the Ivy League women's swimming and diving championships at Harvard University, Saturday, Feb. 19, 2022, in Cambridge, Massachusetts. (AP Photo/Mary Schwalm)

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But the wins didn’t come without scrutiny and put a sharper focus on the governing bodies of various sports to set rules regarding transgender athletes’ participation.