While President Donald Trump has a public suspicion of declaring a national emergency as a way to set up a border wall, some Republicans are worried about the precedent that such a move could create for future Presidents – and Democrats.

Trump seems more and more inclined to turn to a national emergency to divert funds to a wall on the US-Mexico border, while the partial closure of the government reaches its 21st day Friday.

"If we do not reach agreement with Congress, I will most likely do it," Trump told Fox News host Sean Hannity in an interview for Thursday. "I would actually say that I would do it. I can not imagine any reason for that, because I'm allowed to do it. The law is 100% on my side. "

While declaring a national emergency falls within his powers as president, some members of the right are sounding the alarm if Trump does so in the circumstances, allowing future presidents to do the same. And not about immigration, but rather about issues like climate change, health care or other priorities of the Democratic Party, if and when a member of that party lands in the White House.

Senator Marco Rubio (R-FL) stated in an interview with CNBC Squawk Box On Thursday, he was not "ready to approve" Trump's recourse to a national emergency for now and warned of future spin-offs.

"This creates long – term precedents, and I can tell you that for the people on my side, one of the concerns we should have is if today the national emergency situation is the border security and that gives it the right to do something, we all support that. Tomorrow, the security emergency for national security could be, as you know, climate change. So let's grab the fossil fuel plants or something like that, "he said. "It may be an exaggeration, but what I mean is that we must be very careful not to endorse broad uses of executive power in our republic."

Senator Marco Rubio said that he was not ready to support Trump in declaring a national emergency on border security because under a Democratic president, "the urgency of national security could be climate change". pic.twitter.com/2taNpiW5Nr

– Rebecca Harrington (@HarringtonBecca) January 10, 2019

Representative Matt Gaetz (R-FL) put forward an argument against the slippery slope in an interview with the Wall Street Journal. "I do not want the next national emergency to be such that a Democratic president says we need to build transgender toilets in all primary schools in America," he said.

The Wall Street Journal editorial board issued a warning on Thursday, saying that if the courts could potentially intervene on Trump's emergency declaration, there was no guarantee that it would happen.

"If Mr. Trump wins in court, a president, Elizabeth Warren, could consider the precedent as an authorization to bypass the Congress whenever it would be politically expedient," wrote the editorial board. "The increase in carbon emissions or even income inequality could be declared national emergencies."

Even Fox News warned against a national emergency declaration. Fox and friends Facilitator Brian Kilmeade said Thursday that it would be "a disaster as a whole, and that this would show us that we are incompetent and unable to govern around the world". He added that it would create a "terrible precedent".

Republicans have complained of Obama's excessive outreach. Do not do it on Trump is a bad look.

For years, Republicans have publicly worried about Barack Obama's presidential potential. Now, Trump is suspicious of declaring a national emergency – even if there is not one – and they are a bit stuck. They want to support the president. They also do not want to look bad, or put in place a scenario in which future presidents use a similar game.

Jane Coaston of Vox recently explained Republican concerns:

Among conservatives, including those who strongly support a border wall, the debate over a possible national emergency declaration was less focused on whether a wall of the style that Trump had promised time and again during the campaign was necessary, rather than on the powers of a president, and should have.

"Do we really want to create the precedent that the president can simply declare" it's an emergency "as a magic incantation, and then completely circumvent the property rights and the will of Congress so that he can stand his ground. Election promise, if Sam Nunberg is to believe, started as a consultant gimmick for Trump to talk about immigration and his talent as a builder? "wrote Monday Jonah Goldberg, editorialist for the conservative publication The National Review.

"If President Trump begins to imitate Barack Obama by issuing dubious decrees and flouting private property rights, he may find himself in trouble, even with portions of his base," wrote John Fund in a separate article from the National Review last weekend.

Until now, Democrats seem rather reluctant to the idea that Trump declares a national emergency and have decried his threats to do so. Some, however, have at least jumped on the idea jokingly.

"Pumped by the next Democratic president to use" emergency powers, "Thursday joked Thursday on Twitter Jon Favreau, former Obama speechwriter and co-founder of Crooked Media, a comparable future to that of the Republicans.

Pumped up for the next Democratic president to use the "emergency powers" for a Green New Deal, Medicare for All and a new voting law (Democratic Urgency)! https://t.co/cuC19W6nkH

– Jon Favreau (@jonfavs) January 10, 2019

If Trump declared a national emergency to cross the boundary wall, the move would certainly be closely scrutinized and subject to judicial challenge in the courts. Congress could also overturn it by a two-thirds majority in both houses, and it is unclear how this will unfold.

Trump could at least take the first step: under the National Emergency Act of 1976, the president can issue an emergency declaration and rely on some 130 laws already codified by Congress to try to build the wall. His legal team is already finding ways to do it.