Responding in their own televised remarks, Democratic House Speaker Nancy Pelosi and Senate Minority Leader Chuck Schumer accused Trump of misrepresenting the situation on the border as they urged him to reopen closed government departments and turn loose paychecks for hundreds of thousands of workers.
Pelosi, D-Calif., said Trump forced the shutdown due to "his obsession" with a costly, ineffective wall, which she recently called "immoral". "So sad. So awful".
The speech is scheduled for 9 p.m. EST from the White House.
The debate over funding for the barrier has been at the center of a partial federal government shutdown. Sanders said Trump "lies all the time", citing the president's assertions that Mexico would pay for the wall and his claims about the number of terrorists and amount of illegal drugs flowing across the border. Less than a week after Democrats seized control of the House, Pelosi and Schumer stood side-by-side at a lectern in a joint appearance that appeared created to emphasize their party's unity.
His impulsive political instincts can go into overdrive after appearances in which he put on a calm presidential demeanor, for instance, in his State of the Union address previous year.
World Cup winner Pavard to join Bayern Munich from July 1
He has featured 14 times for a struggling Stuttgart this season, with the club now 16th in the Bundesliga table. Bayern Munich have agreed a deal to sign French World Cup victor Benjamin Pavard from Stuttgart this summer.
Trump also suggested that other people, including rich liberals, build walls "not because they hate the people outside but because they love the people inside".
Trump is demanding $5.7 billion for the wall, an idea Democrats reject as costly and ineffective in protecting US security.
The House has passed legislation to reopen the government while negotiations over a border wall continue. And Senate Democrats have approved similar funding year after year. Vice President Mike Pence met privately with House Republicans, urging them to "stand strong" and insisting the White House wants to negotiate, according to people familiar with the conversation. But he says having failed, Trump is now "unable to convince Congress or the American people to foot the bill".
AP writers Colleen Long, Alan Fram and Deb Riechmann contributed.