Until Friday, when Quinnipiac University released a new survey. Clinton 44, Sanders 42. It's the closest result yet.

It's also a dramatic shift since Quinnipiac's poll at the end of December. Since then, Clinton has lost 17 points of support and Sanders has gained 12 -- a massive shift. A ... hard-to-believe shift.

Clinton led by 31 then, now leads by 2. She led with men by 19, now trails. Led with women by nearly 40 points, now leads by 10.

Quinnipiac also found that Clinton's favorability ratings sank, while Sanders's mostly stayed the same. That can help explain why poll numbers shifted.

At this point, it's hard not to assume that this poll is an outlier, a survey conducted with totally acceptable methodology and sample size that just happens to be at one extreme of the margin of error. If you look at the average of recent polls, Clinton's lead hasn't collapsed in the way Quinnipiac suggests. (And this average includes Quinnipiac's poll.)

One other nugget from the new poll is that Americans think Sanders would do a better job against the Republican nominee, whoever it is. He beats Donald Trump by a wider margin than Clinton, beats Ted Cruz (where she ties) and ties Marco Rubio (where she loses).

All of this said: Clinton still leads, and national polls aren't terribly predictive. Clinton is still the front-runner on the Democratic side, at least for now.

Incidentally, that first poll from 2012 in the Real Clear Politics list? This was its title.