Democrats responded to President Donald Trump's declaration of a national emergency on Friday by calling for executive action on what they say are more pressing crises, including gun violence and climate change.

"Our next President should declare a #NationalEmergency on day 1 to address the existential threat to all life on the planet posed by Climate Change," Rep. Ilhan Omar argued.

Acting White House chief of staff Mick Mulvaney brushed off concerns that Trump has set a new precedent for future presidents with his declaration.

Democrats on Friday responded to President Donald Trump's declaration of a national emergency to build barriers on the United States' border with Mexico by calling for national emergencies to address what they say are more pressing issues, including gun violence and climate change.

On Thursday, House Speaker Nancy Pelosi slammed Trump's unilateral move to redirect funds to build an extension of the border wall as an unconstitutional "end run around Congress."

She argued that the president should instead declare a national emergency over the "epidemic of gun violence in America," citing the one-year anniversary of the mass shooting at Stoneman Douglas High School in Parkland, Florida on Thursday.

"Want to talk about a national emergency? Let's talk about today," Pelosi said, referring to the Parkland shooting. "That's a national emergency. Why don't you declare that emergency, Mr. President? I wish you would."

Pelosi added that the move sets a new precedent for future administrations and that she doesn't support any president bypassing Congress to make policy.

See more: Nancy Pelosi slams Trump's plan to declare a national emergency to fund the border wall, argues that he should declare one on gun violence instead

Sen. Chris Murphy, a Connecticut Democrat and particularly outspoken proponent of gun control, picked up on Pelosi's argument on Friday.

"100 people die from guns every day," he tweeted. "That's a national emergency."

Rep. Ilhan Omar, a progressive freshman Democrat from Minnesota, argued that if Trump can declare a national emergency on the border, "Our next President should declare a #NationalEmergency on day 1 to address the existential threat to all life on the planet posed by Climate Change."

Democrats also argued that the declaration is an unconstitutional reaction to Congress' unwillingness to fully fund the border wall. And many, including Rep. Alexandria Ocasio-Cortez, charged Trump with "faking a crisis."

But in a conference call with reporters before Trump's announcement on Friday, Mick Mulvaney, the acting White House chief of staff, brushed aside concerns that the president's move is unprecedented and illegal.

"I saw Nancy Pelosi said yesterday this sets a precedent for the Democrats to declare a gun emergency the next time they're in the Oval Office. That's completely false," he added. "If Democrats could've figured out a way to do it, they would have done that already."