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 TrumpTrump directed Cohen to lie to Congress about plans to build Trump Tower in Moscow during 2016 campaign: report DC train system losing 0k per day during government shutdown Senate Republicans eye rules change to speed Trump nominees 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 ObamaBarack Obama wishes Michelle a happy birthday: 'You’re one of a kind' NY Times prints special section featuring women of the 116th Congress Former congressmen, RNC members appointed to Trump administration roles 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: Trump unveils new missile defense plan | Dems express alarm | Shutdown hits Day 27 | Trump cancels Pelosi foreign trip | Senators offer bill to prevent NATO withdrawal McConnell blocks bill to reopen most of government Bipartisan senators reintroduce bill to prevent Trump from withdrawing from NATO 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 CornynTrump tells GOP senators he’s sticking to Syria and Afghanistan pullout  Texas governor, top lawmakers tell Trump not to use hurricane relief funds to build border wall The Hill's Morning Report — Trump’s attorney general pick passes first test 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.