Joining California in the suit, he said , will be Hawaii, Minnesota, New Mexico and Oregon.

“We are prepared,” he said. “We knew something like this might happen, and with our sister state partners, we are ready to go.”

In a Sunday interview on ABC’s “This Week , Becerra said the legal fight will be undertaken “definitely and imminently.”

NEW: California Attorney General Xavier Becerra says the state will file a lawsuit “definitely and imminently” against the Trump administration over the president's recent national emergency declaration. https://t.co/PhozbB3Mne pic.twitter.com/mqUjroQ1pA

On Friday, Trump made the national emergency declaration in his latest bid to obtain billions of dollars to fund the wall he has long pledged to build along the U.S. border with Mexico. His move came as he signed a bill allocating $1.375 billion for various border security measures, including some barriers ― a sum far short of what he sought.

Even as he claimed the emergency declaration was necessary to thwart what he claimed are drugs and criminals pouring into the U.S. across the southern border, he simultaneously admitted, “I didn’t need to do this.”

Becerra pointed to that comment Trump made in the White House Rose Garden as showing the declaration was unwarranted. With that comment, “he himself said” he wasn’t acting because of an emergency, Becerra said of Trump.

“He’s hoping that he can count on a conservative court in the Supreme Court to give him a victory because he knows he’s going to lose all the way up the ladder of the courts ― the federal court system.”

Citizens for Responsibility and Ethics, a Washington organization, has already filed a suit and the American Civil Liberties Union intends to do the same.