"President Trump must stop holding the American people hostage, must stop manufacturing a crisis, and must re-open the government," Speaker of the House Nancy Pelosi said in a curt rebuttal to Trump's address to the nation minutes earlier, in which he declared the situation on the southern border a "crisis of the heart."
The political impasse over Trump's border wall demand — and the divided Congress's refusal to fund it — has kept key government agencies closed for the past 18 days, with few signs that a breakthrough is imminent.
And with Democrats reclaiming the majority in the House of Representatives, Trump has lost his monopoly on congressional power that could have helped him reach an agreement with lawmakers.
About 800,000 federal workers, and many more contractors, are not being paid, but Trump said that problem could be resolved swiftly if Democrats simply "fund border security."
In a sombre appeal to the nation, Trump spoke of Americans who have been "savagely murdered in cold blood" by immigrants who crossed illegally into the United States.
"How much more American blood must we shed before Congress does its job?" he pleaded.
The Democrats rejected Trump's fear-mongering as "misinformation and even malice," with Pelosi blasting the president's "obsession with forcing American taxpayers to waste billions of dollars on an expensive and ineffective wall."
Top Senate Democrat Chuck Schumer, standing with Pelosi in the US Capitol, accused Trump of throwing a "temper tantrum" over the border, where he "appealed to fear, not facts."
"No president should pound the table and demand he gets his way or else the government shuts down, hurting millions of Americans who are treated as leverage," Schumer said.
"The symbol of America should be the Statue of Liberty, not a 30-foot wall," he concluded.
Rank-and-file lawmakers from both sides of the political aisle weighed in quickly on social media, with Republicans praising Trump for outlining the facts of a national security crisis on the border and Democrats attacking him for misleading and dividing Americans.
"Throughout history, presidents have used an Oval Office address to bring the country together," tweeted Adam Schiff, chairman of the House Intelligence Committee.
"Tonight, Trump used it to stoke fear and division."
The political impasse over Trump's border wall demand and the divided Congress's refusal to fund it has kept key government agencies closed for the past 18 days.