Throughout his four years in office, President Donald Trump’s rhetoric on immigration was unparalleled. Trump’s willingness to brazenly insult immigrants and ethnic minorities directly played into his role as a right-wing populist hero. Unfortunately, while in that position, Trump and the Trump Administration’s treatment of immigrants and immigration policy was often characteristic of anti-democratic behavior, anti-democratic behavior Trump would justify with more right-wing populist rhetoric.
There are many characteristics for what could be defined as anti-democratic behavior, but some key examples include instances of executive aggrandizement, violating generally accepted norms, and attacking pluralism.
Similarly, there are many characteristics for what can be considered populist. Ipek Çinar, Professor Susan Stokes, and Andres Uribe outlined how populists can fit into the description of being anti-elitist Manicheans, those who are “using harsh language against opponents and framing themselves as a moral savior.” While previous, “traditional,” versions of populism focused on what would largely be considered leftist thought of criticizing economic elites, right-wing populism criticizes “political elites and ethnic out groups,” something Trump matches. 
The importance of norms for a functioning democracy cannot be overstated. These norms, as described in How Democracies Die by Professors Steven Levitsky and Daniel Ziblattt, are “shared codes of conduct that become common knowledge within a particular community or society – accepted, respected, and enforced by its members,” they are the unwritten rules that prevent our leaders from engaging in legal but anti-democratic behaviors. 
In his time in office, Trump broke several fundamental norms dealing with immigration in service of his racist, populist rhetoric. One of the most significant norms in American politics is mutual toleration, the idea that we may not like when our opponents utilize or gain power, but we have to accept and recognize them as legitimate. Trump failed this norm continuously throughout his presidency, and he often achieved this by utilizing populist rhetoric against any opponent he might have. When Judge Gonzalo Curiel refused to dismiss a Trump University lawsuit, Trump employed populist rhetoric by framing Judge Curiel as part of an ethnic minority out-group and attacking him, claiming that he was biased against Trump thanks to his heritage and immigration history. This level of attack on the judiciary would be cause for concern on its own, but Trump’s invoking of right-wing populist rhetoric is important because it’s his justification for this anti-democratic behavior.
Another instance of democratic erosion that is relevant here is executive aggrandizement. In Dr. Nancy Bermeo’s work, On Democratic Backsliding, executive aggrandizement is described as executives weakening “checks on executive power one by one, undertaking a series of institutional changes that hamper the power of opposition forces to challenge executive preferences.”  Trump’s rhetoric regarding the checks on power matches these types of actions, as Trump utilized racist rhetoric on immigration to attack the institutions that could check his power.
By framing immigration in a Manichean, us vs. them, good vs. evil type of issue, Trump used illegal immigrants as scapegoats in any failure he had, including his inability to win the popular vote. While this is already an incredibly childish action, Trump was drawing serious doubt onto our electoral system, which is supposed to check executives, by using populist rhetoric and was setting up the groundwork for further anti-democratic actions on this issue. Trump continued his forms of executive aggrandizement by attacking Congress and departing from our understanding of Congress’s checks on the presidency. One of the most valued checks in the US checks-and-balances system is the check of Congress having the power of the purse. Its purpose is so that the executive and Congress work together to ensure funding for the projects the executive might want. When Congress refused to give in and give Trump everything he wanted for his border wall, he shifted money that had been allocated for military spending over to his border wall plans. Trump justified this sidestep and erosion of the checks-and-balances system in the same way he justified everything regarding immigration and his border wall, that the wall was necessary to save the country and stop illegal immigrants.
This action also matches another facet of populism, as Jan-Werner Müller claims in his book What is Populism?, “populists are always anti-pluralist. Populists claim that they, and they alone, represent the people.”  Trump matches this description in the example above as he refused to work with other members of government to achieve his goals. He also utilized populist rhetoric on this issue to attack his political opponents, promoting “Trump style divisiveness,” over traditional US alliance-building. Trump’s appeal to minority voters was that Hillary Clinton was going to ruin their lives and chances of getting a job by bringing in “millions of new low-wage workers to compete against them.”  Again, Trump was utilizing populist styles of rhetoric to excuse his anti-democratic behavior, saying he was the only one who could solve this, so voters should accept everything he does and hate his opponents who were against “the people.”
While many may criticize the above writing, saying that Trump isn’t a populist, rhetoric isn’t important in judging our leaders and doesn’t fit into cases like executive aggrandizement that are about actions, or even that Trump’s actions here are justified, I disagree. First, to the last point, Trump’s actions on the issue of immigration constitute instances of erosion. He ignored checks on his power and other branches of government, and he broke many democratic norms and principles. With that in mind, the issue of rhetoric is justifiably concerning as, while it’s true that rhetoric alone isn’t an example of weakening a check on a balance of power or breaking a norm, it was Trump’s rhetoric that justified these anti-democratic actions. He attacked the judiciary based on a judge’s heritage and immigration history and sidestepped Congress and their check of control of funding over the need for a border wall to keep out immigrants. Finally, on the first point that Trump’s rhetoric does not match that of the populist, Trump’s blatant anti-pluralism and promotion of divisiveness, painting his opponents and political elite as devils and him a savior, fit the anti-elitist and Manichean aspects perfectly, and his anti-immigrant and racial minority rhetoric firmly planted him in the right wing-populist category.
References: Ipek Çinar, Susan Stokes, and Andres Uribe, “Presidential Rhetoric and Populism” Presidential Studies Quarterly 50, No. 2 (June 2020): 242 Steven Levitsky and Daniel Ziblatt, How Democracies Die, (New York: Broadway Books), 2018. 102 Nancy Bermeo, “On Democratic Backsliding” Journal of Democracy 27, No. 1 (January 2016): 10 Jahn Werner-Mueller, What is Populism?, (Philidelphia: University of Pennsylvania Press), 2016, 3 Ipek Çinar, Susan Stokes, and Andres Uribe, “Presidential Rhetoric and Populism” Presidential Studies Quarterly 50, No. 2 (June 2020): 255