This study uses computational methods to investigate public incivility in Facebook comments to campaign messages during the primaries of the 2016 U.S. Presidential Election, focusing on candidates' posts about immigration. Specifically, we investigate the relationship between campaign messaging strategies, such as advocacy and attacks, and the presence of incivility in public comments. We find that Trump dominated both in terms of number of posts and of public conversation and was the least likely to receive uncivil comments. Attack messages by the candidates were more likely to receive uncivil comments, suggesting that campaign negativity may indeed affect how the public engages with candidates online. These findings are important because uncivil discourse may contribute to further polarize the public around the issues, which may in turn lead to more extreme views.