EXCLUSIVE: The All-American swimmer who became an outspoken advocate for women's athletics after competing against transgender swimmer Lia Thomas is supporting Sen. Rand Paul's re-election bid, and she says Paul is "not afraid to fight for fairness" in a new campaign ad.

"I trained from an early age, giving it my all to achieve my dream," Riley Gaines says in the 30-second ad. "And I accomplished it, becoming a 12-time All-American swimmer at the University of Kentucky. But for girls across America that dream is being taken away by men competing in women’s sports. Sadly, few stood up for me."

"But Rand Paul is not afraid to fight for fairness for women and girls, and that’s why I’m supporting him," she says.

The Kentucky Senator has been an outspoken critic of transgender athletes competing in sports corresponding with their gender identity. "I will always fight for fairness," Paul says in the ad.

Rand Paul senator transgender sports Riley Gaines

Sen. Rand Paul, R-Ky. (Greg Nash-Pool/Getty Images)

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Gaines competed against Lia Thomas, the transgender swimmer for the University of Pennsylvania, during her senior year in the 200-meter race at the NCAA Championships, one of the most competitive events in swimming. After tying with Thomas down to the hundredth of a second, Gaines said Thomas was given the trophy for "photo purposes" while Gaines had to wait for hers to be sent to her in the mail.

Gaines told Fox News Digital in an interview that she thinks the Biden administration is "absolutely not pro-women" and is pursing "regressive" policies.

She said Paul’s support "makes you a lot more confident as someone who is in this position to speak your mind. It means a lot to have someone in his position willing to do that for female athletes, willing to do that for people’s daughters."

"No one wants their daughter in the situation that myself and other female athletes have been in," Gaines said. "So, to have someone willing to fight for that, it really means a lot."

A photo illustration of Lia Thomas and Riley Gaines

University of Pennsylvania swimmer Lia Thomas, left, and Kentucky swimmer Riley Gaines (Rich von Biberstein/Icon Sportswire via Getty Images)

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Gains said she took "for granted" Title IX, the 1972 civil rights law that prohibits sex discrimination. She said it was not until her senior year of college that she realized the "sacrifice and the fight these women put in to get to the point that we were at. And now that it’s kind of unfolding before my eyes to what it looked like before … it is so heartbreaking."

While Gaines believes the Biden administrations' policies are "absolutely not pro-women," both Paul and Gaines said the issue of fairness in women’s sports transcends politics.

"I hate that this is even political. I don’t even think it should be," Gaines said.

"Most people in this country don’t think this is right. But I will say the people who do think it is right are typically on the left. And so, I think they’re looking at this as progressive," she said. "But this is so far from progressive. This is totally regressive. It’s a 180 to what people fought the last 50 years for."

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"It’s not really a Republican or Democrat issue — no one thinks this is fair," said Paul, who also spoke with Fox News Digital. "It just defies all common sense for anybody to believe that men should compete with women."

Riley Gaines at the Swimming and Diving Championships

Kentucky swimmer Riley Gaines swims the 200 butterfly prelims at the NCAA Swimming and Diving Championships on March 19, 2022, at McAuley Aquatic Center in Atlanta. (Rich von Biberstein/Icon Sportswire via Getty Images)

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"Title IX was created to enforce equal opportunities for woman," Gaines said. "But we’ve gotten to the point where we’re infiltrating men back into that equation, and it’s taking opportunities away from women. So, therefore, it’s doing the exact opposite of what Title IX was created to protect from."

The junior GOP Kentucky senator is up for re-election on Nov. 4.