Originally Published: 10 AUG 20 13:14 ET

By Jennifer Hansler, CNN

(CNN) -- Senate Democrats are seeking answers from the State Department after a number of cases in which the children of same-sex US parents born abroad did not have their birthright citizenship recognized.

The letter to Secretary of State Mike Pompeo, led by Sen. Tim Kaine of Virginia and signed by fellow Democrats on the Senate Foreign Relations Committee, states that they "are deeply concerned by the growing number of reports indicating that the State Department may have deliberately altered internal guidelines regarding the processing of citizenship transmission for children born to U.S. citizens abroad in a manner disproportionately inhibiting same-sex married couples from transmitting citizenship to their children."

"The crux of the issue appears to be the State Department's overriding focus on biological parentage of a child when determining eligibility for transmission, rather than the marital status of the child's parents," the Monday letter said. "The Department's insistence that a child is only born 'in wedlock' if the child is biologically related to both of its married parents appears contrary to U.S. law as well as to American values. The lack of enforcement of similar strictures on opposite-sex couples raises serious constitutional concerns."

The lawmakers requested a briefing for their staff on the matter as well as a "schedule for the review and revision of this policy."

A State Department spokesperson said they do not comment on correspondence with Congress.

A number of same-sex couples have sued the Department after their children were denied birthright citizenship under a policy that considers them "born out of wedlock."

Under the policy on "assisted reproductive technology," there are a number of circumstances in which a child is considered "born out of wedlock." For example, "a child born abroad to a surrogate, whose genetic parents are a U.S. citizen father and anonymous egg donor, is considered for citizenship purposes to be a person born out of wedlock."

Critics of the policy say it unduly targets LGBTQ families.

"When a straight couple is using surrogacy, or when a straight couple is using an egg donation or sperm donation, nobody asks them if they are the biological parents of the child, it's just an assumption. But when an LGBT family's coming and applying, our application was flagged as surrogacy," Adiel Kiviti told CNN last year.

He and his husband Roee Kiviti sued the State Department last year after their daughter, who was born in Canada using an egg donor and a surrogate mother, did not have her US citizenship automatically transmitted.

In June, a federal judge ordered the State Department to recognize her birthright citizenship and grant her a US passport.

The ruling found that the department's refusal to grant Roee and Adiel Kiviti's daughter, Kessem, a passport "contravenes the United States Constitution, the Immigration and Nationality Act ... and the Administrative Procedure Act."

The Kivitis are not the only LGBTQ family to have sought legal recourse to the policy. According to a release from Immigration Equality, theirs was one of four suits filed against the State Department by the LGBTQ immigrant rights organization. A federal judge ruled in favor of another same-sex couple who faced a similar hurdle under the State Department's surrogacy policy last February. The State Department appealed that ruling.