Story highlights An aide to Bernie Sanders "threw a fit" when CBS informed the campaigns in a conference call

CBS stood by its change and representatives for Hillary Clinton and Martin O'Malley's campaigns agreed to the change

(CNN) The Democratic presidential candidates are squaring off on stage, but behind-the-scenes drama preceded the event as organizers announced changes just hours before it started to accommodate questions regarding the Paris terror attacks.

A call with all three Democratic campaigns, CBS and members of the Democratic National Committee about how to address the terrorist attacks in Paris quickly turned contentious Saturday over those specific changes.

An aide to Bernie Sanders "threw a fit" when CBS informed the campaigns in a conference call Saturday that the Democratic debate would kick off with a focus on the attacks in Paris, a person who was on the call told CNN.

"Once CBS informed the campaigns the debate was going to kick off with a focus on the attacks in Paris last night, he (Mark Longabaugh, a Sanders strategist) completely lost it. He threw a fit for several minutes," the source said.

But a DNC debate coordinator tells CNN that the argument on the call earlier Saturday was not about whether the debate would focus on Paris, adding that it is unfair to say Sanders' campaign did not want to debate foreign policy.

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