As expected, President Trump's controversial national emergency declaration faces a tortuous road before it can officially get off the ground.

Just a few days after his announcement, a coalition of 16 states has introduced a federal lawsuit to block Trump’s border wall project, arguing that his decision to bypass Congress and obtain appropriated funds from other departments is "unconstitutional."

According to the Washington Post, the legal move headed by states with Democratic governors, and represented by the Attorney General of California, Xavier Becerra, seeks "a preliminary injunction that would prevent the president from acting on his emergency declaration while the case plays out in the courts."

The documentation was filed in the San Francisco-based Northern District Court of California. It seeks to protect residents, natural resources and economic interests from President Trump's “flagrant disregard of fundamental separation of powers principles.”

After not obtaining the funds he had asked for his wall, Trump has decided to resort to the Department of Defense's $3.6 billion budget allocated for military construction.

The president would also be able to take advantage of $600 million from the Treasury Department's drug forfeiture fund, and $2.5 billion from a drug interdiction program, also from within the Department of Defense budget, should the national emergency declaration stand.

This wave of lawsuits is no surprise to anyone, especially for Trump, who during his announcement last Friday anticipated the development of events.

"We will have a national emergency, and we will then be sued, and they will sue us in the Ninth Circuit, even though it shouldn't be there," Trump said from the Rose Garden in the White House, "and we will possibly get a bad ruling and then we will get another bad ruling, and then we will end up in the Supreme Court, and hopefully we will get a fair shake and win in the Supreme Court, just like the ban…"

However, it’s precisely the president's own words that have served as "best evidence" for the class action lawsuit, and members of the coalition such as Attorney General Becerra have warned that this is their best ammunition.

"President Trump, keep talking. We continue to gather evidence to support our lawsuit against you," Becerra posted in response to a string of angry tweets from the president upon learning of the coalition.

According to ABC News, the lawsuit "cites Trump's own words as the ‘best evidence’ his declaration of an emergency was invalid," echoing the president's statement at the time of saying, "I didn’t need to do this, but I’d rather do it much faster.”

Several non-profit organizations have also announced their intentions to introduce simultaneous suits, and on Monday several cities held street demonstrations against the declaration.

For its part, the Democratic majority in the House of Representatives "has vowed to challenge the president's declaration when it returns from recess next week," Politico reported.

New York representative Alexandria Ocasio-Cortez and Texas representative Joaquín Castro have already introduced a resolution to terminate the presidential move.