DES MOINES — In the hours after the deadly attacks in Paris, CBS News significantly reworked its plans for the Democratic presidential debate it is hosting here on Saturday night to focus more on issues of terrorism, national security and foreign relations.

Steve Capus, the executive editor of CBS News and the executive producer of “CBS Evening News,” said in an interview late Friday that he was in the middle of a rehearsal for the debate when news broke about the slaughter in Paris.

The CBS News team immediately shifted gears and reformulated questions to make them more directly related to the attacks. Mr. Capus said it was important for the debate to go on because the world looks to the American president for leadership during international crises.

“American leadership is put to the test,” Mr. Capus said. “The entire world is looking to the White House. These people are vying to take over this office.”