President Donald Trump declared Tuesday that he would prevail over a multistate lawsuit challenging his emergency declaration to pay for a U.S.-Mexico border wall.

Speaking to reporters at the White House, Trump said he expected to do "very well," against the suit, adding that he had an "absolute right" to make the declaration.

"I think in the end we're going to be very successful with the lawsuit," Trump said, arguing that the opposition was political.

A group of 16 states, including California, New York and Colorado, filed a lawsuit Monday against Trump's emergency declaration. The lawsuit filed in the 9th U.S. Circuit Court of Appeals in San Francisco alleges Trump's declaration is unconstitutional.

All the states involved in the lawsuit have Democratic attorneys general.

The American Civil Liberties Union on Tuesday filed its own separate lawsuit in a U.S. District Court in California, alleging that "Trump disregarded the will of Congress with his emergency declaration."

'No one is above the law'

Using a broad interpretation of his executive powers, Trump declared an emergency last week to obtain wall funding beyond the $1.4 billion US that Congress approved for border security. The move allows the president to bypass Congress to use money from the Pentagon and other budgets.

Democrats have seized on the move as an example of executive overreach.

The office of House Speaker Nancy Pelosi issued a release Tuesday that stated: "No one is above the law. Republicans must join Democrats to uphold the Constitution and stand with the American people against the President's brazen assault."

Sixteen states — led by California — have joined to sue the Trump administration over the U.S. president's declaration of a national emergency to fund a wall on the U.S.-Mexico border. (Margo Reed/The Philadelphia Inquirer/Associated Press)

Trump argued Tuesday that the wall was needed to "stop drugs and crime and criminals and human trafficking."

He has repeatedly sought to paint a dire picture of conditions at the border, though illegal border crossings are down from a high of 1.6 million in 2000.

After weeks spent battling with Congress over border funding and what constituted a wall versus a fence, Trump said: "I can call it a barrier, but I think I don't have to do that so much anymore, we'll call it whatever we want."

Trump prepared to veto

Trump's use of the emergency declaration has drawn bipartisan criticism and is expected to face numerous legal challenges. A top White House adviser said Sunday that Trump was prepared to issue his first veto if Congress votes to disapprove his declaration of a national emergency.

Earlier Tuesday, Trump singled out California for its lead role in the suit, seeking to link the state's high-speed rail project to his plan for the wall.

Protesters turned out in cities across the country including New York, Washington, and Philadelphia. (Go Nakamura/Reuters)

By Tuesday afternoon, the administration announced plans to cancel $929 million US for California's beleaguered high-speed rail project and wants the state to return an additional $2.5 billion it's already spent on the planned train between Los Angeles and San Francisco.

The federal money comes with certain requirements that the Trump administration said California won't meet.

California Gov. Gavin Newsom said the Trump administration is engaging in "political retribution" by trying to take back $3.5 billion US granted for the state's high-speed rail project.

The Democratic governor said President Donald Trump is reacting to California suing over Trump's emergency declaration to pay for a wall along the U.S.-Mexico border.

As I predicted, 16 states, led mostly by Open Border Democrats and the Radical Left, have filed a lawsuit in, of course, the 9th Circuit! California, the state that has wasted billions of dollars on their out of control Fast Train, with no hope of completion, seems in charge! —@realDonaldTrump Trump linked the two together Tuesday in a tweet that referenced the lawsuit and said California "has wasted billions of dollars on their out of control Fast Train."

Newsom said California won't sit "idly by" and will fight to keep the money.