The poster uses "Trump" four times to create the image of a swastika, with the word "Stop" written below in large capital letters.

An anti-Trump protestor also held up a sign that depicted Trump with a mustache like Adolf Hitler's and read "Absolutely No Mexicans."

Sign outside Ted Cruz's polling place in Houston pic.twitter.com/JY6hhXnzZv — Ben Jacobs (@Bencjacobs) March 1, 2016

Anti-Trump protester says Trump is a white supremacist, a Nazi and supporter of the KKK pic.twitter.com/1wV7K79WCN — Ben Jacobs (@Bencjacobs) March 1, 2016

A new sign appeared at this Houston polling location. Was hastily removed. #SuperTuesday @realDonaldTrump pic.twitter.com/ZkgO0f3P9u — Emily Cahn (@CahnEmily) March 1, 2016

Last week, former Mexican president Vicente Fox said Trump reminded him of Hitler, noting the front-runner has offended "everybody."