WASHINGTON, Jan. 7 (Xinhua) -- U.S. President Donald Trump has been considering declaring a possible national emergency to acquire the money for building his pledged wall on the U.S.-Mexico border, Vice President Mike Pence said Monday.

"He's made no decision on that," Pence told reporters in a briefing, adding that officials at the White House council's office "are looking at" a possible emergency declaration, and "the president is considering it."

Democratic lawmakers have repeatedly rejected Trump's demand that 5.6 billion U.S. dollars be added to the 2019 budget to fund the border wall. As both parties refused to budge in their stance on the wall funding issue, a quarter of federal agencies have been dysfunctional due to a lapse in congressional appropriations since Dec. 22, 2018.

On Monday afternoon, Trump tweeted that he will address the nation on "Humanitarian and National Security crisis on our Southern Border," without disclosing what decision will be announced during his televised speech on Tuesday evening.

In recent days, Trump has been floating the idea of declaring a national emergency so that he can extract money from the Department of Defense to pay for the wall, bypassing congressional approval. Democrats said Trump will face legal challenges if doing so.

"I may declare a national emergency dependent on what's going to happen over the next few days," the president reiterated his intention while meeting the press on Sunday.

"The president's position is: There is a crisis at the southern border, and Democrats are refusing to negotiate," Pence said, urging the Democrats to return to the negotiating table for a solution to end the ongoing partial government shutdown.

Pence and his team held talks with congressional Democratic staffers Saturday through Sunday, but they failed to reach an agreement. Pence noted that the Democrats said they would not negotiate until the government was reopened.

In an effort to reopen the government, House Democrats on Thursday passed two separate bills, but Senate Republicans didn't take them up since neither included money for the wall.

"A wall is an immorality, it's not who we are as a nation...We are not doing a wall," House Speaker Nancy Pelosi told reporters after the passage of the bills in the House.