(CN) - The Anti-Defamation League is calling on Donald Trump's oldest son to apologize for making what appeared to be a Holocaust-themed joke.
In an interview with Philadelphia radio station 1210 WPHT on Wednesday, Donald Trump Jr. accused the Democrats of rigging their primary system.
"The media has been her number one surrogate in this. Without the media, this wouldn't even be a contest, but the media has built her up," Trump told program host Chris Stigall. "They've let her slide on every discrepancy, on every lie, on every DNC game trying to get Bernie Sanders out of this thing. If Republicans were doing that, they'd be warming up the gas chamber right now."
The ADL, an international anti-Semitism organization, tweeted Thursday that "trivialization of the Holocaust and gas chamber is NEVER ok."
The group then tweeted that its members hoped Trump Jr. understood the "insensitivity and hurt" caused by his joke and asked for an apology.
Hillary Clinton's campaign was quick to jump on the younger Trump's comments.
Sarah Bard, Clinton's Director of Jewish Outreach, said the remarks showed "just how insensitive, divisive, and reckless the Trump campaign is."
"The bottom line is this — offensive references to the Holocaust are never acceptable, especially from a presidential campaign," Bard said in a statement.
The Trump campaign said Thursday the candidate's son was not making a reference to the Holocaust.
"Don Jr. was clearly referring to capital punishment to make the case that the media continues to take words out of context in order to serve as the propaganda arm of the Hillary Clinton campaign — something that's only gotten worse as Trump's poll numbers have improved," Jason Miller, the campaign's senior communications advisor, said in a statement.
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