The announcement comes as the longest government shutdown in U.S. history approaches a month in length.
In a video posted to Twitter Friday evening, Trump called the situation at the southern border both a "humanitarian crisis" and a "national security crisis." He added that it would be necessary to secure the border and that "if we don't do that, we're a very, very sad and foolish lot."
The president's promised announcement comes amid an acrimonious back-and-forth with Democratic leaders over the protracted government shutdown and funding over his long-desired border wall.
The bitter words continued Friday. House Speaker Nancy Pelosi, whose official trip overseas on a military aircraft was abruptly blocked Thursday by Trump, accused the president and his administration of leaking her plans to possibly fly commercially instead and endangering lives as a result.
"After President Trump revoked the use of military aircraft to travel to Afghanistan, the delegation was prepared to fly commercially to proceed with this vital trip to meet with our commanders and troops on the front lines. In the middle of the night, the State Department's Diplomatic Security Service provided an updated threat assessment detailing that the President announcing this sensitive travel had significantly increased the danger to the delegation and to the troops, security, and other officials supporting the trip," Hammill said.
Due to "grave threats" the delegation decided to postpone the trip, Hammill said.
The White House called the assertion a "flat out lie."
Meanwhile, hundreds of furloughed federal workers waited on Friday to get free food at a pop-up kitchen on Pennsylvania Avenue -- not far from the White House and Capitol -- on day 28 of the government shutdown. A similar scene played out in cities such as Atlanta, San Francisco and New Haven, Connecticut.