Fox News legal analyst Andrew Napolitano on Monday expressed skepticism over President TrumpDonald John TrumpPentagon update to missile defense doctrine will explore space-base technologies, lasers to counter threats Giuliani: 'I never said there was no collusion' between the Trump campaign and Russia Former congressmen, RNC members appointed to Trump administration roles MORE's legal standing to declare a national emergency to direct the construction of his desired wall along the southern border.

“The president has valid emergency authorities in a time of a true emergency, but he can’t spend money and he can’t take property unless the Congress is authorized it. That’s directly from the Constitution," Napolitano told Fox News anchor Martha MacCallum on "The Story."

"Otherwise he’s bypassing the Congress and he’s not a president, he’s a prince," he added.

ADVERTISEMENT

Napolitano cited the Supreme Court decision during the Truman administration that struck down then-President Harry Truman's efforts to nationalize the steel industry via a national emergency declaration. Several Democrats have used that precedent to raise legality concerns about Trump's threat to declare a national emergency.

The retired judge on Monday added that Trump would have to prove the country is facing a true emergency because of the state of affairs at the southern border.

"The numbers are very impressive, but an emergency is defined… as when the government is overwhelmed and its ordinary assets don’t work," he said. "I don't think President Trump would say that."

Trump has said he's considering declaring a national emergency to direct construction of his desired border wall. Democrats have said such a move would face certain legal challenges, while Republicans have said they'd rather the president not skirt Congress with such a measure.

The president's request for more than $5 billion in funding for his desired border wall has triggered a partial government shutdown that has lasted 17 days and counting. Democrats have offered $1.3 billion for border security, but no money for the wall.

Trump is set to deliver a primetime address about the situation on Tuesday, and will travel to the border on Thursday.