Meanwhile, “problems that should engage our energy are forced to the back of the queue of public attention. The normal constitutional approaches to governing — bills passed through committees, compromises reached in conferences involving both parties and both houses of Congress — are no longer respected… The real national emergency is the triviality of our politics.”
Washington Post

“Illegal immigration has declined 75 percent since 2000. The only real emergency here is the way that Trump is misusing the powers of the presidency. The solution… is for Congress to codify many of the unwritten expectations of presidential conduct and to constrain the president’s vast discretion. But that won’t happen anytime soon because Republican members of Congress have violated an important norm of their own: They are putting their loyalty to the president and their political party above their loyalty to the country and the Constitution.”
Washington Post

“Congress has yielded more and more power to the executive branch over decades. In many areas, it has reduced the legislative branch to a mere pedestrian in government, leaving real governing decisions to a kind of ‘fourth branch’ of federal agencies. For their part, presidents have thus become more and more bold in circumventing Congress. When Obama gave a State of the Union proclaiming his intention to bypass Congress after it failed to pass immigration reform, Democrats applauded loudly… Congress has been heading to hell for decades, and it is a bit late to complain about the destination.”
The Hill

“Congress could readily specify certain conditions that must exist before the president can make such a declaration… magnitude (the feared incremental harms of the condition are very large, not just marginal); geographic scope (those harms should be nationwide even if the triggering condition is more localized); extraordinary (the condition should be rare, if not unprecedented); imminence (the anticipated harms should be so close in time that Congress cannot deliberate); and likely effectiveness… In the long run, this is more crucial to the vitality of our democracy than whether President Trump ultimately gets his wall.”
New York Times

Regarding the non-emergency portion of the funding, according to the director of the Project on Government Oversight’s Center for Defense Information, while “‘the Pentagon’s budget can be trimmed in places, it shouldn’t be at the expense of national security and certainly not for a border wall.’ It is anticipated that $3.5 billion will come from the military construction budget, which is intended to improve military bases, many of which are in dire need of overhaul…

“[He] is expected to tap an additional $2.5 billion from DOD’s drug interdiction operations, targeting drugs coming into the United States at official ports of entry… Cutting this part of DOD’s budget ‘will significantly undermine the capacity of the department to address that mission.’”
ThinkProgress