(Reuters) - New York and Washington state on Monday vowed to sue President Donald Trump if he scraps a program shielding from deportation immigrants who came to the United States illegally as children.

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The Trump administration is expected to announce on Tuesday that he will end the so-called Dreamers program but give the U.S. Congress six months to craft legislation to replace it, according to sources familiar with the situation. [nL2N1LL01P]

U.S. Attorney General Jeff Sessions will announce plans for ending the Deferred Action for Childhood Arrivals, or DACA, program at 11 a.m. (1500 GMT) on Tuesday, but will not take questions, the Justice Department said on Monday.

New York Governor Andrew Cuomo, in a joint statement with the state’s attorney general, Eric Schneiderman, said, “The president’s action would upend the lives of hundreds of thousands of young people who have only ever called America their home.”

The attorney general of Washington state, Bob Ferguson, also threatened legal action. “I will use all the legal tools at my disposal to defend the thousands of Dreamers in Washington state,” he said in a statement.

Ferguson and Schneiderman were among 20 attorneys general who wrote to Trump in July to say that if he ended the program, they would defend it “by all appropriate means.”

Nine Republican state attorneys general have said they would file suit on Tuesday if Trump did not end the program.

The White House declined to comment on Monday.

DACA is a policy created by former President Barack Obama that protects nearly 800,000 young people, often called “Dreamers,” from deportation and allows them to work legally.

Under the shift Trump is considering, any Dreamer with a valid work permit would be able to remain in the United States until the permit expires, in the absence of congressional action, sources familiar with the matter said.

At the same time, the Department of Homeland Security would not target Dreamers for deportation, one of the sources said.

Dreamers are a fraction of the estimated 11 million illegal immigrants in the United States, most of them Hispanic. Trump as a candidate promised to deport all of them, but many Americans have rallied to support the young adults, who have spent large parts of their lives in the United States.

While Republicans in Congress have generally taken a hard line on illegal immigration and are sympathetic to the argument that Obama overstepped his bounds in creating DACA, several have stepped forward to call for action to protect the Dreamers.

House of Representatives Speaker Paul Ryan, the top elected Republican official, on Friday urged Trump not to rescind the program, as did Senator Orrin Hatch. Senator James Lankford said on Monday it was not appropriate to “hold children legally accountable for the actions of their parents.”

Another Republican, Senator Tom Cotton, who has been particularly outspoken on reforming immigration laws, told the Washington Examiner he supports legislation that would protect dreamers and take legal steps to reduce illegal immigration.

Many prominent business leaders, including the chief executive officers of Microsoft MSFT.O, General Motors GM.N and Facebook Inc FB.O -- Satya Nadella, Mary Barra and Mark Zuckerberg, respectively -- have also urged Trump not to reverse the Dreamer program.