Who would've guessed the NRA using the Boston bombing to rail against gun control would be the second most controversial thing to come out of its annual convention.
Glenn Beck fired up the group's Houston gathering this weekend with his attacks on New York City Mayor Michael Bloomberg ... who he likened to Hitler.
The head of the Anti-Defamation League called Beck's latest stunt "deeply offensive on so many levels." B'nai B'rith also called on Beck to apologize:
"Glenn Beck, the keynote speaker at the NRA's annual convention, trivializes the Holocaust by comparing New York City Mayor Michael Bloomberg to Adolf Hitler."
"The casual use of Nazi imagery or words serves to undermine the atrocities of the Holocaust. Glenn Beck should apologize," the group told ABC News.