Acting on behalf of two expectant mothers, migrant advocates in Boston Tuesday filed one of the first legal challenges to President Trump’s effort to end birthright citizenship enshrined in the U.S. Constitution.

In a lawsuit filed in US District Court in Boston just after midnight Tuesday, advocates from three organizations requested a formal declaration from the courts that Trump’s executive order is both unconstitutional and illegal.

“This unprecedented attempt to strip citizenship from millions of Americans with the stroke of a pen is flagrantly illegal. The President does not have the power to decide who becomes a citizen at birth,” the lawsuit asserts. “That right is conveyed by the first clause of the Fourteenth Amendment to the U.S. Constitution…”

The lawsuit was filed by Lawyers for Civil Rights, La Colaborativa, and the Brazilian Worker Center on behalf of the expectant mothers.

A parallel lawsuit was filed in US District Court in New Hampshire by the American Civil Liberties Union and its chapters from New Hampshire, Maine, and Massachusetts. Also participating is the Asian Law Caucus, State Democracy Defenders Fund, and Legal Defense Fund on behalf of on groups whose members have children directly affected. Those groups are the New Hampshire Indonesian Community Support, League of United Latin American Citizens (LULAC), and Make the Road New York.

Trump issued the executive order, one of dozens, on Monday following his inauguration for a second term. In the text of the order, the administration argues that a child born of at least one parent who is “unlawfully present” in the country is not protected by the 14th Amendment of the Constitution.

“The Fourteenth Amendment has always excluded from birthright citizenship persons who were born in the United States but not ‘subject to the jurisdiction thereof,’ ” according to the text.

Birthright citizenship was added to the Constitution as part of the 14th Amendment in 1868 and was embraced as a means to ensure formerly enslaved people during Reconstruction were granted the same legal protection as other citizens.

If ultimately successful — which would require amending the Constitution — the change could have a major impact in New England. In Massachusetts, about 30,100 children with US citizenship had at least one undocumented parent as of 2022, according to a report from the American Immigration Council, the Globe reported.

One of the women, identified as O. Doe in the lawsuit, is due to deliver her child in March and plans to live in Massachusetts. She is lawfully in the US under Temporary Protected Status, issued for migrants from troubled countries like Haiti, but the father of her child is not a US citizen or lawful permanent resident, according to the lawsuit.

More than 27,000 Massachusetts residents, both newly arrived and immigrants who have lived here for decades, had Temporary Protected Status as of this spring, the Globe reported.

The advocates contend that Trump’s focus on birthright citizenship is designed to punish a “group of U.S. citizens based only on their parents’ immigration status” and that it has severe implications for children born in the US.

“Those victimized in this way by the [Trump executive order] would be shorn of their national identity, stigmatized in the eyes of those who should be their fellow citizens, and forced to live with the shame, uncertainty, and fear that comes with potential banishment from their native country,” the advocates asserted in the lawsuit. “Many would be rendered immediately stateless.”

The lawsuit contends that the Trump order would create a second class of citizens in violation of the due process clause of the Fifth Amendment.

“And because the EO treats the targeted citizens as a subordinate caste of native-born Americans, entitled to fewer rights, benefits, and entitlements than other Americans due to their parents’ alienage, it also violates their right to equal protection under the Due Process Clause of the Fifth Amendment,” the lawsuit alleges.

According to court records, no hearing date on the litigation has yet been set.

A Framingham mother, who asked that her last name not be used for fear of attracting the attention of immigration officials, has a 5-year-old, American-born daughter and two adolescent daughters who were born in Brazil. She and her husband, also Brazilian, must decide who will care for their youngest if they are deported without her, the Globe reported.

Information from earlier Globe reporting was used in this account.

Read the complete lawsuit below:

John R. Ellement can be reached at [email protected]. Follow him @JREbosglobe.