The new coronavirus is spreading rapidly in pockets across America, and in the latest move to curb its transmission, a one-mile "containment zone" has been established in New Rochelle, New York. The illness appears to be more dangerous for older populations, which has many wondering what the candidates for president will do. President Trump is 73, and his Democratic challengers are both in their late 70s. (Former Vice President Joe Biden is 77, and Vermont Sen. Bernie Sanders is 78.)

John King, host of CNN's Inside Politics, told Boston Public Radio on Tuesday — when six states vote in their primaries — whether the candidates change their campaigning style might depend on how much of a delegate difference they can put between each other.

"We are at a key moment in the Democratic primaries where Joe Biden has opened up a modest but significant delegate lead, and if he stretches it out tonight, I think a lot of people are going to think mathematically — not that Senator Sanders is going to get out — but mathematically Joe Biden has a chance tonight to make a huge statement here," said King. "If we get to that point, do the candidates campaign less? Do they campaign in different ways?"

King said it's not a matter of if, but when.

"I think it is inevitable that the behavior changes some going forward, but the answer is how much."