California Attorney General Xavier Becerra said Sunday that a lawsuit against the Trump administration for the president's recent national emergency declaration would be coming "imminently," marking one of the many legal challenges the White House can expect in its efforts to fund the president's long-promised border wall. Becerra told ABC News' "This Week with George Stephanoplous" that the state is "ready to go" with legal action and is expecting to be joined by numerous other state partners.

According to the attorney general's office, New Mexico, Oregon, Minnesota, New Jersey, Hawaii and Connecticut are among several states that are joining the lawsuit.

Mr. Trump on Friday announced the emergency declaration to free up funding to build the border wall along the southern border. The executive order said "the current situation at the southern border presents a border security and humanitarian crisis that threatens core national security interests and constitutes a national emergency."

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Becerra told ABC's Martha Raddatz that he's confident the state has concrete legal standing to challenge the president's order.

"We're confident there are at least 8 billion ways that we can prove harm. And once we are all clear, all the different states are clear, what pots of money that taxpayers sent to D.C. he's going to raid, which Congress dedicated to different types of services – whether it's emergency response services or whether it's fires or mudslides in California or maybe tornadoes and floods in other parts of the country or whether it's our military men and women and their families who live on military installations that might – that might have money taken away from them, or whether it's money taken away from drug interdiction efforts in places like California, a number of states, and certainly Americans, will be harmed. And we're all going to be prepared," said Becerra.

The California attorney general said Mr. Trump "knows he's going to lose in court" and suggested that a conservative-leaning Supreme Court could be his only way to secure a victory. "He knows he's going to lose all the way up the ladder of the federal court system," said Becerra .

There have been 58 national emergencies declared since the National Emergencies Act was passed in 1876, including three by Mr. Trump. Thirty-one of those national emergencies are still in effect. Becerra claimed however, that this specific declaration is "dubious" at best.

"Typically, our presidents have focused on issues where the national interests are clearly at stake. The national interests aren't at stake here. We have the lowest level of entries into the country by those that don't have permission than we've had in some 20 years. The Department of Homeland Security itself has said to the president that it is more difficult to cross into the U.S. at our land borders than it has been in a long time. And so it's clear that this isn't an emergency, it's clear that in the mind of Donald Trump he needs to do something to try to fulfill a campaign promise," said Becerra.

In addition to California's lawsuit, the American Civil Liberties Union announced its intention to sue less than an hour after the White House released the text of Mr. Trump's declaration. Nonprofit watchdog group Public Citizen later filed suit, urging the U.S. District Court for the District of Columbia to "bar Trump and the U.S. Department of Defense from using the declaration and funds appropriated for other purposes to build a border wall."

House Speaker Nancy Pelosi also hasn't ruled out taking legal action against the administration if a resolution to reverse the declaration fails.