WASHINGTON — President Donald Trump intensified threats Thursday to invoke his “emergency powers” to build his border wall if Democrats don’t cooperate, saying his lawyers have looked into the matter and “they tell me 100 percent” he can.

Critics have denounced the idea as abusive and unlawful, but experts on presidential powers and immigration enforcement say that Congress has granted Trump, and presidents before him, wide latitude to invoke emergency powers. He also has a sympathetic Supreme Court that has demonstrated willingness to back him in the event of a court challenge.

“Congress has left very broad powers in the hands of whoever is president to declare emergencies for reasons vague, imagined or real,” said Michael Waldman, president at the Brennan Center for Justice. “And presidents have a lot of power when they do that.”

The Brennan Center for Justice has identified 136 statutory powers that a president can invoke just by signing his name.

Trump first raised the prospects of using his emergency powers on Friday during a news conference in the Rose Garden. The new Democratic chairman of the House Armed Services Committee, Rep. Adam Smith of Washington, later appeared to agree with him, but warned he’d be “wide open to a court challenge.”

“Unfortunately, the short answer is yes,” Smith said during an interview on ABC’s “This Week.”

Trump raised the prospect again on his way to McAllen, Texas, Thursday, where he’ll continue his campaign for a wall across the U.S.-Mexico border. He told reporters that he’s checked with his lawyers if he can use federal funds without congressional approval. They told him yes, he said.

“I have the absolute right to declare a national emergency,” Trump said. “I haven’t done it yet. I may do it. If this doesn’t work out, probably I will do it. I would almost say definitely.”

Trump’s bravado on Thursday demonstrated how entrenched the two sides remain on the 20th day of the partial government shutdown that doesn’t appear to be ending soon. But some former Trump officials question whether substituting this fight with another drag-out court battle over his presidential authority is in his best interests.

“He’s trying to maximize his leverage. That’s what any good negotiator does,” said one former Trump administration official. “The question is it a really feasible solution. … There will be a lawsuit filed 30 minutes after he signs.”

But Leon Fresco, who defended some of the Obama administration’s most controversial enforcement policies as deputy assistant attorney general for the office of immigration litigation, said Trump could win a prolonged court fight. Fresco said he’d likely lose a battle in lower courts, but that a friendlier Supreme Court could support him.

Even before the Trump-nominated Justice Brett Kavanaugh took the oath, the Supreme Court has demonstrated its willingness to give Trump wide leeway on presidential powers.

In a 5-4 ruling, the high court upheld Trump’s controversial travel ban that barred nearly all travelers from five mainly Muslim countries as well as officials from North Korea and Venezuela.

And last month, the court nearly allowed the Trump administration to deny asylum to those who illegally cross the U.S.-Mexico border despite language in the law that states asylum applications from people who had entered the country unlawfully.

“Any alien who is physically present in the United States or who arrives in the United States (whether or not at a designated port of arrival and including an alien who is brought to the United States after having been interdicted in international or United States waters), irrespective of such alien’s status,” the statute says.

If not for Chief Justice John G. Roberts Jr., a conservative nominated by President George W. Bush, Trump would have even more leeway.

Fresco said the asylum statute is clear, but Roberts is less likely to rule against Trump on the wall.

“Why not?” Fresco said. “The question is can you name a more appropriate military construction project than to build a barrier to stop an unlawful incursion into the United States.”

The Supreme Court has never pushed back on an emergency declaration under the National Emergencies Act, according to the Brennan Center of Justice. But Waldman said there are limits to the president’s executive powers.

He pointed to one of those famous instances when the Supreme Court blocked President Harry Truman from nationalizing the steel industry during the Korean War.

“So there is a history of the court standing up to this kind of thing,” Waldman said. “The question for this court is will they follow in the path of courts that did stand up to presidential abuses of power or not.”