How shall we define "The Wall"? 500 miles? 1000 miles? So far, I think about 50 miles have been constructed.
The southern border is about 2000 miles. It's unrealistic to expect 100% coverage given the geography. Barricades along 1000 miles will give the Border Patrol much more leverage to do their job, as it will to discourage illegal immigrants.
The Secure Fence Act was voted in favor of by BOTH parties and signed by 'W' back in 2006 -- it was never fully funded and if memory serves correctly about 700 miles of fencing was erected here an there.
It is NOT unrealistic to expect that some form of barrier protect the entire border.
The problem has never been about approval (since both parties agreed to a fence) but $$$. Trump now has the $$,and he has always had the authority to defend our borders --- he just hasn't done it because of convenient excuses, especially since he had a full majority for 2 years. My books, there is no excuse. There is no excuse that he signed a bill allowing states to opt out. There is no excuse that he offered up amnesty.
Now he's contemplating adding red flag laws. Neither equates to him being re-electable.
He claims to be Mr. 2A himself, he needs to prove it. Otherwise, he WILL lose in 2020. No doubt in my mind.