The Trump administration must stop applying a discriminatory policy that denies citizenship to some children born abroad to same-sex couples, 19 senators and 80 representatives said Thursday in letters to Secretary of State Mike Pompeo.

The government treats some children born outside the United States to same-sex married couples as “born out of wedlock” ― a distinction that requires them to be biologically related to a U.S. citizen parent in order to be considered a citizen themselves.

The senators’ letter, spearheaded by Sens. Jeff Merkley (D-Ore.) and Kamala Harris (D-Calif.) and first reported by the Daily Beast, highlights Andrew and Elad Dvash-Banks, who sued after only one of their twin sons was granted citizenship. Ethan and Aiden were born in Canada in 2016 within minutes of one another from the same surrogate, each from one father’s sperm. The married dads submitted DNA test results to the American consulate in Toronto as part of their application for their sons’ citizenship. The result: the biological child of Andrew, a U.S. citizen, was granted citizenship, but the biological child of Elad, an Israeli citizen, was not.

The senators criticized the State Department for “bizarrely” defining the birth of the Dvash-Banks sons as “out of wedlock” and noted that other families have experienced similar treatment. The policy “threatens the constitutional right of citizenship for children of same-sex couples when those children happen to be born abroad,” the senators said.

The signers of the senators’ letter included four Democratic presidential hopefuls: Harris, Sen. Cory Booker (D-N.J.), Sen. Amy Klobuchar (D-Minn.) and Sen. Bernie Sanders (I-Vt.).

The Immigration and Nationality Act does not require a biological relationship between a child born abroad and a parent who is a U.S. citizen for that child to qualify for citizenship. But, under State Department practice, children of legally married same-sex couples who are born through a form of assisted reproductive technology are considered “born out of wedlock,” which means citizenship for that child born abroad requires proof of a biological relationship to a parent with citizenship.

While some straight couples have faced similar challenges with children born overseas when only one partner holds U.S. citizenship, the policy is most often applied to same-sex couples, the Dvash-Banks’ attorney Aaron C. Morris told The Washington Post.

Eighty House members sent a similar letter to Pompeo on Thursday calling out the State Department for treating same-sex couples “differently than their different-sex counterparts,” according to the Daily Beast. Reps. Deb Haaland (D-N.M.), David Cicilline (D-R.I.) and Tom Malinowski (D-N.J.) led the letter and it was signed by all members of the House who are gay, lesbian or bisexual, according to the Daily Beast.