(CNN) Republican Sen. Susan Collins said Wednesday that she supports a lawsuit challenging President Donald Trump's national emergency declaration and that she plans to vote in favor of a congressional resolution aimed at halting the declaration.

"I disagree with the President's decision to invoke the National Emergencies Act. I don't think that is what the law was intended for. It was intended for catastrophic events, such as the attacks on our nation on 9/11 and severe natural disasters," Collins, who represents Maine, said at an event in the state. "I do support the lawsuit that was filed by the states. I think that may be the quickest way to get an injunction that would halt this transfer of funds."

Last week, Trump declared a national emergency in order to unlock billions of dollars in federal funds to build a wall along the US-Mexico border. On Monday, 16 states filed states filed a lawsuit in the US District Court for the Northern District of California, arguing that the President is circumventing Congress in order to pay for the wall.

Collins, a key swing vote in the Senate who's up for re-election in 2020, said that the move "completely undermines the role of Congress in the appropriations process," adding that it is "of dubious constitutionality."

The senator said that she plans to vote in favor of a resolution halting the national emergency that will be introduced in the House on Friday before it moves to the Senate.

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