"I would hate to see it," Republican Senator Ron Johnson from Wisconsin said. "I would prefer not, primarily because, if we do that, it's going to go to court."
As of Friday, at least eight Republican senators, ranging from moderate swing voters to loyal allies, have at least cautioned the president against declaring a national emergency.
But a path to citizenship for foreigners in the U.S. on temporary, speciality work visas would almost certainly require Congressional approval.
Republican Senator Lindsey Graham said Thursday that he supported the idea of President Donald Trump declaring a national emergency to fund and build a wall on the U.S.-Mexico border.
Russia's space agency chief and former deputy prime minister, Dmitry Rogozin, called U.S. actions "an outrage" and a display of "complete international lawlessness."
House Speaker Nancy Pelosi questioned President Donald Trump's motives for allowing the partial shutdown of the federal government to continue and called the standoff a "distraction."
"It would just be a disaster in the big picture and just show us being inept and unable to govern around the world, and it would just set a terrible precedent," host Brian Kilmeade said on "Fox & Friends."
"When, during the campaign, I would say Mexico is going to pay for it, obviously I never said this, and I never meant they're going to write out a check," the president told reporters.
"Cryin' Chuck told his favorite lie when he used his standard sound bite that I 'slammed the table and walked out of the room,'" the president said on Twitter.
It may have only been a metaphor but it was somehow prescient.
Nancy Pelosi's comments came immediately after a meeting at the Oval Office where Trump abruptly left over a disagreement on funding for the border wall.
"I can stand up and say they are right because it's the right thing to do for this country," Mark Morgan said.
Of all the networks, CBS pulled in the largest audience, with more than 8 million viewers tuning in for the address and rebuttal.
Undocumented migrants pay more than $20 billion in taxes annually, according to the IRS.
Federal employee union leaders and Democratic leaders slammed the president's speech and accused him of holding the government hostage.
As Twitter lit up with responses to President Donald Trump's televised address, conservatives including Donald Trump Jr. and Megyn Kelly criticized a joke by the "Late Night With Seth Meyers" account.
"Sarah, there were some discrepancies with some numbers," 'Fox & Friends' co-host Ainsley Earhardt said.
"I think certainly I have expressed more than a few times the frustrations with a government shutdown and how useless it is," Senator Shelley Moore Capito of West Virginia told CNN.
Democratic strategist gives damning criticism of president's first prime-time Oval Office address.
The freshman congresswoman doubled down on the accusation she made during an interview with Anderson Cooper on Sunday.
"The emergency declaration," Andrew Napolitano said, "allows him to mobilize assets, but it doesn't allow him to take or occupy property, and it doesn't allow him to spend money the Congress hasn't authorized."
The vice president said Trump got the "impression" past administrations wanted a wall, but Trump claimed some former presidents had told him directly.