Sen. Bob Casey, D-Pa., weighed in on transgender females competing in sports against athletes of the same gender they identify as. 

Casey wrote a letter in June 2023, which stated that the concerns over biological males' participation in female sports are "overgeneralized." He also suggested the concerns on the issue were based on "unfounded assumptions."

"The decision to transition is a profoundly significant and challenging one that young adults make after careful consideration. This is a conclusion that young adults reach after extensive consultation with their medical providers and loved ones, and with the knowledge of the tremendous social obstacles that unfortunately lie ahead," Casey wrote in a letter obtained by the Daily Caller.

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Sen. Bob Casey, D-Pa.

Sen. Bob Casey, D-Pa., leaves the Capitol in Washington, D.C., after a vote on April 18, 2023. (Bill Clark/CQ-Roll Call, Inc via Getty Images)

"All young people should have the opportunity to enjoy recreational sports and have their personal dignity respected. In a world where transgender youth face a disproportionate risk of bullying, harassment and violence, allowing transitioning youth to participate in athletics in their affirmed gender can provide enormous social and psychological benefits. Rather than stigmatizing vulnerable youth, I believe we can and should create inclusive and informed guidance that allows all students to flourish," Casey added.

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Fox News Digital contacted Sen. Casey's office and requested additional comment on the letter, but did not immediately receive a response.

Senator Bob Casey speaks during an event

Sen. Bob Casey, D-Pa., speaks during the Inaugural Independence Dinner in Philadelphia on Nov. 1, 2019. (Bastiaan Slabbers/NurPhoto via Getty Images)

In 2021, the British Journal of Sports Medicine published a study that transgender women maintain an advantage over biological women even after a year of hormone therapy treatment.

"For the Olympic level, the elite level, I'd say probably two years is more realistic than one year," Dr. Timothy Roberts, the director of the adolescent medicine training program at Children's Mercy Hospital in Kansas City, Missouri, told NBC News at the time. "At one year, the trans women on average still have an advantage over the cis women."

In April, the National Association of Intercollegiate Athletics (NAIA) banned transgender athletes from competing in women’s sports.

NAIA building

The National Association of Intercollegiate Athletics headquarters is shown on March 26, 2020. (Jamie Squire/Getty Images)

The NAIA said it supported "fair and safe competition for all student-athletes" and that "Title IX ensures there are separate and equal opportunities for female athletes." The organization laid out its participation rules with conditions.

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"Participation by students in sports designated as male by the NAIA: All eligible NAIA student-athletes may participate in NAIA-sponsored male sports," the organization said.

"Participation by students in sports designated as female by the NAIA: Only NAIA student-athletes whose biological sex is female may participate in NAIA-sponsored female sports."

The NAIA said a student who has not begun "any masculinizing hormone therapy may participate without limitation."

Fox News' Ryan Gaydos contributed to this report.

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