Speaking to the nation from the Oval Office for the first time, Trump argued the wall was needed to resolve a security and humanitarian "crisis," blaming illegal immigration for what he said was a scourge of drugs and violence in the US and asking: "How much more American blood must we shed before Congress does its job?"
Democrats in response accused Trump appealing to "fear, not facts" and manufacturing a border crisis for political gain, AP reported.
Using the formal trappings of the White House, Trump hoped to gain the upper hand in the standoff over his demand for $5.7 billion to build a wall along the US-Mexico border. He plans a visit to the border Thursday as he continues to pitch what was a signature promise of his 2016 presidential campaign.
He addressed the nation as the shutdown stretched through its third week, with hundreds of thousands of federal workers going without pay and some congressional Republicans growing increasingly jittery about the spreading impact of the impasse. Trump claimed the standoff could be resolved in "45 minutes" if Democrats would just negotiate, but previous meetings have led to no agreement.
TV networks had been reticent about providing Trump airtime to make what some feared would be a purely political speech.
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.
Negotiations on wall funding could proceed in the meantime, they said.
Schumer said Trump "just used the backdrop of the Oval Office to manufacture a crisis, stoke fear and divert attention from the turmoil in his administration."
In his dire address, Trump ticked off a string of statistics and claims to make his case that there is a crisis at the border, but a number of his statements were misleading, such as saying the new trade deal with Mexico would pay for the wall, or suggesting through gruesome examples that immigrants are more likely to commit crime.
Trump, who has long railed against illegal immigration at the border, has recently seized on humanitarian concerns to argue there is a broader crisis that can only be solved with a wall. But critics say the security risks are overblown and the administration is at least partly to blame for the humanitarian situation.
Trump used emotional language, referring to Americans who were killed by people in the country illegally, saying: "I've met with dozens of families whose loved ones were stolen by illegal immigration. I've held the hands of the weeping mothers and embraced the grief-stricken fathers. So sad. So terrible."
Trump has been discussing the idea of declaring a national emergency to allow him to move forward with the wall without getting congressional approval for the billions he's requested. But he did not mention that Tuesday night.
The partial government shutdown reached its 18th day, making the closure the second-longest in history. Hundreds of thousands of federal workers are going without pay, and government disruptions are hitting home with everyday Americans.