The reason why the Democratic Party is often accused of supporting “open borders” is because, to the ears of many voters, the practical implications of Democratic policy sounds awfully like…open borders.
Very few Democrats say that they actually support “open borders.” But when asked if the United States should have a wall on its border, most Democrats say “No.” (There are already fences on some parts of the border, but many voters don’t know that.) And when asked if illegal immigrants in America should be deported, most Democrats also say “No.”
The result is that many voters add these two things together, and the product sounds a lot like…“open borders.” To use an analogy, it would be like someone saying, “I do not support shoplifting at Walmart.” But when asked, “Do you support Walmart installing an anti-shoplifting system at its stores?” this person says “No.” When asked, “Should shoplifters be prosecuted?” the person also replies “No.” Then these two things, combined, make it sound like the person does, in fact, condone shoplifting at Walmart, even if that’s not his intention.