It is worth noting here that although the “wall” is primarily associated with former Pres. Trump’s, the “wall” has wide support within the Republican Party and, despite having rhetorical issues with the term “wall,” increased funding for border “fencing” and other militaristic security measures are widely supported within the Democratic Party as well; this means that if you address any element of party politics in your response [which you are not required to, but may, if you show the relevance of doing so], you must engage with the actual policy positions of the respective political parties.)
As you prepare to answer this question, keep in mind the fact that any “border wall” on the southern US border with Mexico would likely require utilizing eminent domain to seize (with payment) land from property-owners along the border. Also, keep in mind the xenophobic/nationalistic justifications for the “border wall.” Again, you are not explicitly required to address these additional elements unless you view them as relevant to the relationship between the policy proposal and liberalism.