A radicalized gunman murdered 49 people last weekend, and the nastiest election in recent memory got even nastier.

Any lingering hope that the nation would come together like it did after the Sept. 11, 2001, attacks evaporated when Donald Trump took to Twitter on June 12 soon after the gay nightclub shooting in Orlando to say that he "appreciate[d] the congrats for being right about radical Islamic terrorism." The Republican presidential candidate went on to urge President Barack Obama to "resign in disgrace" for not blaming "radical Islam" for the attack.

Trump doubled down the next day, telling conservative news show "Fox and Friends" that "there’s something going on with him [Obama] that we don’t know about.” When The Washington Post reported that Trump has suggested a sitting president was a traitor, he promptly banned the newspaper from covering his rallies.

Obama gave as good as he got, calling Trump's push for a ban on Muslim immigration to the United States a "dangerous" idea and a betrayal of the nation's values. "Where does this stop?" the president asked. "Are we going to start treating all Muslim Americans differently?"