2. The self-defeating open-borders activists
The migrant caravans that now regularly make their way to the U.S. from the south are normally organized by a group called Pueblo Sin Fronteras (People Without Borders), which explicitly calls for open borders and the free movement of people without restrictions. Though the group apparently didn’t directly organize the current caravan, it has provided logistical support, with affiliated activists in Honduras, Mexico, and the United States pushing its open-borders position.
This plays right into the hands of nationalistic xenophobes like Trump and his media cheerleaders, who can point to an ideological agenda behind the caravan that they (justifiably) see as incompatible with the exercise of national sovereignty in the United States. If those who favor a liberal immigration policy hope to prevail, they need to combine that position with an acceptance of the legitimacy of sovereignty and borders — with Americans consciously choosing to accept a high number of immigrants. The quickest and surest way to ensure that severe immigration restrictionism prevails in the United States would be for those who favor a more liberal immigration policy to adopt the explicitly open-borders position that Trump (falsely) claims they already favor.