The bipartisan group, which gathers as many as 58 former national security officials, is to issue the statement on Monday, The Washington Post reported, citing a copy.
The undersigned include former Secretary of State Madeleine Albright, and former Defense Secretaries Chuck Hagel and Leon Panetta.
Trump declared the emergency on February 15 to bypass congressional approval and secure funding for the construction of a wall along the US-Mexico border, which he claims prevents entry into the country of potential “criminals.”
The proclamation followed a 35-day partial government shutdown — the longest in the US’ history — which came after Congress refused to approve the $5.7 billion Trump needs for the wall.
Democrats say the wall is unnecessary and accuse Trump of trying to create the illusion of a security crisis on the border.
The former officials’ statement likewise questioned the “factual basis” underpinning the president’s reasoning.
“Under no plausible assessment of the evidence is there a national emergency today that entitles the president to tap into funds appropriated for other purposes to build a wall at the southern border,” the group said.
The statement said Trump’s insistence comes while the southern border area faces no documented emergency situation linked to terrorism, violent crime, or drug trafficking.
When Trump declared national emergency, most detained immigrants were not criminals, they added.
The group, meanwhile, reminded that illegal undetected crossings from Mexico into the US had decreased from 851,000 to nearly 62,000 between 2006 and 2016.
In early 2017, after Trump banned entry into the US of foreign nationals from seven predominantly-Muslim countries, some of the same former officials wrote a joint declaration, calling the order “a deliberate political decision to discriminate against a religious minority.”