A former Republican congressman says his party would have been up in arms if a Democratic president considered declaring a national emergency over an issue, as President TrumpDonald John TrumpGOP senator introduces bill to hold online platforms liable for political bias Rubio responds to journalist who called it 'strange' to see him at Trump rally Rubio responds to journalist who called it 'strange' to see him at Trump rally MORE threatened to do this week.

Former Rep. Joe Walsh (R-Ill.) tweeted Thursday that Republicans would have been "storming the White House" during if former President Obama ever considered such a plan.

"My side would be storming the White House if Barack ObamaBarack Hussein ObamaTrump takes credit for passing veterans bill that passed under Obama Orlando Sentinel declines to endorse Trump in 2020 Progressive activist: Democratic nominee will 'need to ride a little bit to the center' MORE ever thought about declaring a national emergency," Walsh wrote.

Trump this week threatened to declare a national emergency to reallocate funding for his border wall.

Republican lawmakers met Trump's plans with skepticism, warning that any declaration of a national emergency over immigration would almost certainly be met with court challenges.

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“Although the president does have national emergency declaration powers … this would be a dubious constitutional authority and would clearly be challenged in the courts," Maine Sen. Susan CollinsSusan Margaret CollinsOvernight Defense: US to send 1K more troops to Mideast amid Iran tensions | Iran threatens to break limit on uranium production in 10 days | US accuses Iran of 'nuclear blackmail' | Details on key defense bill amendments Overnight Defense: US to send 1K more troops to Mideast amid Iran tensions | Iran threatens to break limit on uranium production in 10 days | US accuses Iran of 'nuclear blackmail' | Details on key defense bill amendments Senators revive effort to create McCain human rights commission MORE (R) told reporters this week.

“I just don’t think you can repurpose more than $5 billion from the defense budget for purposes unrelated to what the money was appropriated for," she added.

Other Republicans in the Senate concurred, questioning whether such a strategy would truly be faster than the White House reaching a deal on immigration reform and border security with Congress.

“I think it adds new layers of complexity because we know the first thing that will happen is somebody will file a lawsuit, and it won’t be resolved for weeks, maybe months, maybe even years,” Texas Sen. John CornynJohn CornynWillie Nelson on supporting O'Rourke: 'Anything he wants to do, I'm with Beto' Willie Nelson on supporting O'Rourke: 'Anything he wants to do, I'm with Beto' Koch political arm endorses Colorado Sen. Gardner MORE (R) said.

The federal government's partial shutdown, which was sparked by an impasse over funding for a border wall, is in its 20th day with no resolution in sight.