A number of Republican lawmakers have expressed concerns about the ramifications of President Donald Trump declaring a national emergency to fund his border wall."If today, the national emergency is border security ... tomorrow the national emergency might be climate change," Republican Sen. Marco Rubio said on Wednesday.GOP Sen. Chuck Grassley said, "I don't think he should do that. I think it's a bad precedent. And it contravenes the power of the purse that comes from the elected representatives of the people."As president, Trump has the option of declaring a national emergency, but the process could be messy and lead to yet another dead-end in his fight to build a border wall.A number of Republican lawmakers have expressed concerns about the ramifications of President Donald Trump declaring a national emergency to fund the wall he wishes to build along the US-Mexico border.Trump has floated the idea amid an impasse with Democratic lawmakers over border wall funding, which has led to a partial government shutdown. The president on Thursday said he's hopeful Democrats will "compromise" on the issue, but that he's still willing to declare a national emergency if they don't."Either we're going to win or make a compromise," Trump told reporters before departing for a trip to a border city in Texas. "I'm OK to making a compromise. Compromise is in my vocabulary a very strong word. And so, we're either going to have a win, make a compromise because I think a compromise is a win for everybody, or I will declare a national emergency."Read more: Mayor of McAllen, Texas, where Trump is visiting, doesn't support the president's border wallRepublican Sen. Lindsey Graham, a close ally of Trump, has in recent days called on the president to invoke his emergency powers to build the wall.But other members of the GOP are not on the same page.'I don't think he should do that. I think it's a bad precedent.'Republican Sen. Marco Rubio on Wednesday warned Trump that if he declares a national emergency on this issue it could set a precedent that may lead to actions from Democratic presidents in the future that are unpalatable to conservatives."If today, the national emergency is border security ... tomorrow the national emergency might be climate change," the Florida senator saidduring an interview with CNBC.Sen. Marco Rubio said he's not ready to support Trump declaring a national emergency over border security because under a Democratic president, "the national security emergency might be climate change." pic.twitter.com/2taNpiW5Nr' Rebecca Harrington (@HarringtonBecca) January 10, 2019Republican Sen. Mitt Romney of Utah has since echoed Rubio's sentiments."I don't want to see a declaration of national emergency," Romney, a former Republican presidential nominee, told MSNBC on Thursday. "I think that's an action that would be taken in the most extreme circumstances, and, hopefully, we don't reach that."Republican Sen. Chuck Grassley, one of the most influential figures in the Senate, has also voiced concerns about a national emergency.Read more: Mattis reportedly told Trump before he resigned that a national emergency was the most realistic option to get the wall and the Pentagon could help build it"The president is threatening emergency action, a national emergency declaration," Grassley said during an interview with CNBC on Friday. "I don't think he should do that. I think it's a bad precedent. And it contravenes the power of the purse that comes from the elected representatives of the people."If Trump declares a national emergency, Grassley added, "I believe you're going to find it in the courts almost immediately. And the courts are going to make a decision."Sen. Chuck Grassley doesn't believe that President Trump should declare a national emergency to fund his border wall. "I think it's a bad precedent and it contravenes the power of the purse that comes from the elected representatives of the people." https://t.co/DFBbB7MtoY pic.twitter.com/njvUURNF7m' CNBC (@CNBC) January 11, 2019Some members of the deeply conservative House Freedom Caucus have also expressed dismay about Trump's threat to declare a national emergency."I do see the potential for national emergencies being used for every single thing that we face in the future where we can't reach an agreement. That's the slippery slope that I'm concerned about," Freedom Caucus Chairman Mark Meadows, a key ally of Trump, told Politico on Thursday.Declaring a national emergency on a highly politicized issue would be extremely controversial and met with significant legal challengesThe president has the authority to declare a "national emergency" under the National Emergencies Act of 1976.Some legal experts have argued that the president is also granted emergency powers via the Constitution, as it provides him expansive and ill-defined "executive power" while also making him commander-in-chief of the US military.If Trump declared a national emergency to obtain funding for the border wall, he would in effect be bypassing Congress and its constitutionally-defined authority to determine how the US government spends its money. Technically, the president has the power to do this, but it would be a controversial move.Since the National Emergencies Act was passed in 1976, presidents have declared national emergencies 58 times. There are 31 active national emergencies, including three declared by Trump. Most of these have been uncontroversial and involved imposing sanctions on people accused of human rights violations, which is why they've been renewed by multiple presidents.A national emergency declaration on border security, a highly politicized topic, is far more dubious territory.Many experts contend there is not a crisis at the border, as Trump has claimed, and accuse the White House of attempting to mislead the public on immigration so the president can deliver on a lofty, unnecessary campaign promise.Read more: THE TRUTH ABOUT THE BORDER CRISIS: Experts say there is no security crisis, but there is a simple way to fix immigration ' and it's not a wallAs Grassley noted, such an extraordinary move would undoubtedly face major legal hurdles and put the fate of Trump's wall in the hands of the courts.There are well over 100 statutes a president can invoke during times of emergency, and an analysis from the Brennan Center for Justice at New York University School of Law identified two Trump could lean on if he declares a national emergency. These statutes would, in theory, allow Trump to dedicate military resources and funds to the construction of a wall.But there are open questions as to whether it would be legal for Trump to use military funds for a non-military purpose. There's also a debate on the language of the National Emergencies Act, in terms of how an emergency is actually defined and whether the situation at the border constitutes one.Congress could also overturn such a move via a veto-proof majority, though this is a less likely scenario given the GOP controls the Senate.In short, Trump has the option of declaring a national emergency, but the process could be messy and lead to yet another deadend in his fight to build a border wall.SEE ALSO:Why a GOP congressman who represents more of the border than anyone in Congress opposes Trump's wallJoin the conversation about this storyNOW WATCH: MSNBC host Chris Hayes thinks President Trump's stance on China is 'not at all crazy Click here to read full news..