Speaking outside of the White House on Friday as the government shutdown continued with no funding agreement in sight, President Donald Trump threatened to declare a national emergency to build his "border wall" if he doesn't receive the more than $5 billion in funding he's demanding from Congress.

"I can do it if I want," Trump proclaimed in response to a question from a reporter. "We can do it. I haven't done it. I may do it. I may do it."

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Trump's threat to give himself emergency powers to construct what critics have described as a "monument to racism" came shortly after Senate Minority Leader Chuck Schumer (D-N.Y.) said the president warned during a Situation Room meeting that he could "keep the government closed for a very long period of time, months or even years."

"Declaring a national emergency to build the wall would be an abuse of emergency powers," Elizabeth Goitein, co-director of the Liberty and National Security Program at the Brennan Center for Justice, wrote on Twitter following Trump's comments.

"If you needed more evidence that we have a pure autocrat in the White House: Trump is now considering declaring a national emergency in a disgraceful attempt to get funding for his racist border wall," Public Citizen added.

But, as Goitein wrote in The Atlantic recently, the decision to make such a declaration is "entirely within [Trump's] discretion"—and would make "more than 100 special provisions" available to him.

"For instance, the president can, with the flick of his pen, activate laws allowing him to shut down many kinds of electronic communications inside the United States or freeze Americans’ bank accounts," she wrote.

"This edifice of extraordinary powers has historically rested on the assumption that the president will act in the country's best interest when using them," Goitein continued. "But what if a president, backed into a corner and facing electoral defeat or impeachment, were to declare an emergency for the sake of holding on to power? In that scenario, our laws and institutions might not save us from a presidential power grab. They might be what takes us down."