Obama declares that a National Emergency exists in the United States, because of things going on in the "Crimean region, and the Situation in Ukraine" ("Executive Order 13660")… And NOT ONE democrat (nor republican) so much as objects; never mind bring up a vote to remove, reverse, or override it, or attempt to challenge it in the Courts…

President Trump declares that a National Emergency exists due to the "current situation at the southern border (which) presents a border security and humanitarian crisis that threatens core national security interests"… And the democrats (along with a good portion of republicans) are going to vote to remove, reverse, or override Trump's "Presidential Proclamation on Declaring a National Emergency"…

So, if I get this right, democrats believe that border problems between Crimea and Ukraine is vitally important, and represents a "National Emergency"; but serious border issues right here in the United States are of little importance, and present no need for a "National Emergency"…

https://www.treasury.gov/resource-center/sanctions/Programs/Documents/ukraine_eo.pdf

President Obama on 6 March 2014, declared a National Emergency with his signing of "Executive Order 13660": By the authority vested in me as President by the Constitution and the laws of the United States of America, including the … National Emergencies Act (50 U.S.C. 1601 et seq.)… I, BARACK OBAMA, President of the United States of America, find that the actions and policies of persons including persons who have asserted governmental authority in the Crimean region without the authorization of the Government of Ukraine that undermine democratic processes and institutions in Ukraine; threaten its peace, security, stability, sovereignty, and territorial integrity… hereby declare a national emergency to deal with that threat…

https://www.whitehouse.gov/presidential-actions/presidential-proclamation-declaring-national-emergency-concerning-southern-border-united-states/

President Trump on 6 February 15, 2019 , declared a National Emergency with his signing of "Presidential Proclamation on Declaring a National Emergency": The current situation at the southern border presents a border security and humanitarian crisis that threatens core national security interests and constitutes a national emergency. The southern border is a major entry point for criminals, gang members, and illicit narcotics… now, therefore, I, DONALD J. TRUMP, by the authority vested in me by the Constitution and the laws of the United States of America, including the National Emergencies Act… hereby declare that a national emergency exists at the southern border of the United States…