Why Republicans support the Wall
There is a simple reason why Republicans support the Wall; they want to be tough on immigration without bashing immigrants.
Although it seems silly to many of us, President Donald J. Trump’s (R-New York) border wall scheme is a brilliant political ploy. To explain, promoting the Wall allows Trump to get tough on immigration while saying nothing about immigrants.
To elaborate, immigrants are people whom potential voters could know. For example, the term immigrant conjures up images of that nice family down the street or great grandfather from Palermo.
Immigration, however, is a concept that divides Americans along ideological lines. For instance, cultural conservatives view immigration as a theoretical and existential threat to America’s future. Meanwhile, progressives and libertarians view immigration as an opportunity to build a stronger nation.
Why Republicans Support the Wall they need Votes
Significantly, Republican politicians need the votes of both libertarians and cultural conservatives. In addition, Republicans need to the votes of ethnic Americans, almost all of whom have immigrant roots.

Moreover, Republicans need the votes of culturally conservative working class Americans. Obviously, many of those working people are immigrants or the children of immigrants.
Notably, immigrant bashing is the kind of thing people remember for generations. For example, Irish Americans voted Democratic for generations, because of 19th Century Republican anti-Catholic propaganda.
Why Republicans support the Wall they want Immigrants’ Votes
Smart Republicans like Trump, understand the Grand Old Party (GOP) will need the votes of today’s immigrants’ children and grandchildren someday. Moreover, history teaches that Mexican-Americans are likely to remember Trump’s remark about rapists long after the Donald is in the grave.
Hence, the GOP needs to find ways of discussing immigration without discussing immigrants. Thus, the Wall is the perfect political ploy for Republicans.

By fixating on the Wall, GOP leaders like President Trump and US Senator Mitch McConnell (R-Kentucky) can attack immigration while saying nothing bad about Mexicans. For example, there is no need for ugly remarks about all Mexicans being drug dealers or rapists.
Republicans support the Wall because they want to do nothing about immigration
Finally, Republicans love the Wall because it allows them to discuss immigration while doing nothing about immigration.
Additionally, any effort to offer a legal path to citizenship for illegal immigrants is sure to frighten cultural conservatives. In particular, many cultural conservatives view non-European, non-White, and non-Christian immigration as a threat to their vision of America.

However, almost all immigrants in today’s world are non-White and often non-Christian. Thus, any effort to increase or rationalize immigration will bring up ugly arguments over race and religion.
The Wall is a Brilliant Political Ploy
In addition, any discussion of religion and immigration will stir up religious prejudice which offends many religious conservatives. For instance, wealthy Jewish and Mormon Americans; whose money Republicans need, find any linking of citizenship and religion threatening.

By discussing the Wall, Republicans avoid such arguments while keeping the anti-immigrant vote. Hence, the wall gives Trump a way to increase the Republican base while offending nobody.
In the final analysis, the Wall is a brilliant political ploy that is terrible public policy and horrendous border security. Under those circumstances, the Wall will not go away soon, no matter how stupid it is.