A day after President Trump signed an executive order aimed at ending birthright citizenship, a group of 18 Democratic state attorneys general joined a legal fight to block the move, calling it unconstitutional.

"What the president did yesterday was unlawful, unconstitutional and indefensible," New Jersey Attorney General Matthew Platkin told NPR.

"We are an immigrant state. We have millions of people in our state who have acquired citizenship through birthright citizenship," Platkin said. “This is the story of our state and America, and it’s enshrined in our (U.S.) Constitution for a reason.

Democratic state attorneys general from New Jersey to California signed on to the lawsuit filed Tuesday in Massachusetts. The city of San Francisco and Washington, D.C., are also suing.

At a news conference on Tuesday, California Attorney General Rob Bonta described Trump's order as "setting a terrible tone for his second term. I have a message for Trump." President Trump, I will see you in court," Bonta added.

On Monday, in another legal action, American Civil Liberties Union files lawsuit order aimed at blocking Trump. "Denying citizenship to children born in the United States is not only unconstitutional, it is a reckless and callous denial of American values," said Anthony D. Romero, executive director of the American Civil Liberties Union. in a statement.

The 14th Amendment, ratified in 1868 after the Civil War, provides that all persons "born or naturalized in the United States and subject to the jurisdiction thereof" automatically become citizens.

This language was crafted and added to the Constitution to establish full civil rights for black Americans, but for more than a century it has been interpreted to also grant rights to all children born on U.S. soil, regardless of the immigration status of their parents how.

in his However, Trump explained that the executive order The amendment is worded to exclude babies born to parents in the United States "illegally" or with "legal but temporary" status.

"This is ridiculous. As you know, we are the only country in the world that does this (automatically grant citizenship)," Trump said Monday night When signing the order. Actually, dozens of other countriesincluding Canada and Mexico, have a form of birthright citizenship comparable to the United States

The Trump administration's interpretation of the 14th Amendment has won growing support from many conservative and Republican leaders.

"Birthright citizenship is not expressly enshrined in the Constitution," said Dan Stein, president of the Federation for American Immigration Reform. "The problem is that, as currently interpreted, the 14th Amendment is undermining the ability to regulate immigration."

But Stein and other advocates of restricting citizenship rights for immigrant children say the executive order will likely be overturned by the U.S. Supreme Court.

"Frankly, I don't think this administration is going to solve this problem because I think the Supreme Court will probably rule in favor of the current approach," said Mark Krikorian, executive director of the Center for Immigration Studies. The group also supports strict controls on immigration.

Stein and Krikorian said Trump's order "furthers" the national conversation about birthright citizenship and could ultimately lead to a constitutional amendment ending the practice.

But amending the U.S. Constitution would require broad support, and a growing number of Democratic leaders, including the governors of California and New York, have expressed opposition. California Gov. Gavin Newsom issued a statement Monday after Trump signed the order. Make a statement Simply put, "It's unconstitutional."