'Tis six days before Christmas and at 8:30 pm, Democrats have a debate — and viewership may be light.

But seriously, folks, debates have never been scheduled like this before.

To give you a sense of how rare it is for primary debates to be scheduled so close to the 25th, I looked at every debate going back to 1948. And only once have we had a debate so close to Christmas, and that wasn't even a real debate; it was a special episode of Meet The Press on December 19, 1999, during which Al Gore and Bill Bradley duked it out on the Sunday morning show.

This is important because primetime viewership tends to dip around the holidays — plus, this debate is on a Saturday, which is very rare because viewership is low on Saturdays and Sundays.

Usually the national parties want people to see their candidates onstage, which is why we've never had a debate this close to Christmas, much less on a Saturday. It is free media. But there's some speculation that the Democratic National Committee scheduled debates on times people don't watch specifically to protect frontrunner Hillary Clinton. This hasn't been substantiated, and a few strategists have told me they believe it was incompetence on the DNC's part, rather than some ploy to keep Clinton off the debate stage. But whatever the reason, by the end of primary season, we're going to have seen a lot less of the Democratic candidates in debates than Republicans.

The first Democratic debate drew a strong audience, with about 15 million people tuning in. But the next one, on Saturday, November 14, was the least-watched debate of the primaries thus far. Meanwhile, the Republicans are coming off a strong showing on December 15, where more than 18 million people tuned in to their debate:

Republican debates are garnering record viewership, and it's paying off as far as engaging their party. About 86 percent of Republicans say they are giving "some" or "a lot of" thought to the election, compared with 74 percent in 2007. Meanwhile, 69 percent of people say they have watched at least once debate, and given the viewership data, it was very likely a GOP debate.