The candidates face each other during the debate. Because of the coronavirus pandemic, their podiums are more spread out than usual.
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The debate is taking place in CNN's Washington studios. There is no live audience.
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Sanders walks by as Biden talks to the moderators after the debate.
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Biden and Sanders' responses to the coronavirus highlighted their unity in opposing President Donald Trump, as both believe he has mishandled this crisis. But they have different approaches and philosophies. Biden is pledging competency that leads voters to harken back to how former presidents responded in a time of crisis. Sanders is promising wholesale change.
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"People are looking for results, not a revolution," Biden said. "They want to deal with the results they need right now."
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Sanders followed up Biden's remarks by saying that it is "not good enough not to be understanding how we got here and where we want to go into the future." The back-and-forth highlighted the key differences between the two candidates.
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A look inside the control room at CNN's studios in Washington.
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Biden looks at a video screen as a taped question is asked.
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The podiums are 6 feet apart, per recommendations from the Centers for Disease Control and Prevention.
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The debate was initially supposed to take place in Arizona with a live audience.
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Biden came into the debate with a significant lead in delegates. Sanders has acknowledged his path to the nomination is narrowing.
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"This is bigger than any one of us," Biden said of the coronavirus epidemic. "This calls for a national rallying."
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Sanders said during the debate that the government should pay for all coronavirus testing and treatment. "Do not worry about the cost right now," he said. "Because we're in the middle of a national emergency."
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A camera crew gets a closer look at the candidates.
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Another behind-the-scenes view of Sunday's debate.
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The two candidates stand farther apart than normal while posing for photos before the debate.
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The moderators look over notes during a commercial break. From left are CNN's Jake Tapper, Univision's Ilia Calderón and CNN's Dana Bash.
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Biden and Sanders bump elbows at the start of the event.
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Tapper looks at his phone before the debate.
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Workers wipe down the podiums before the debate.
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The moderators' table is cleaned and disinfected.
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The stage is cleaned before the debate.
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