Will any of the Dem. candidates run negative TV ads in the primary?

[Mr. Morden]

Prompted by a comment I made in another thread: Correct me if I'm wrong, but I don't think there were any negative TV ads run in the 2008 or 2016 Dem. presidential primary campaigns.  I think there may have been some negative radio ads and the candidates of course went after each other on the debate stage, but I don't think Clinton ran any negative TV ads against Obama or vice versa, and same with Clinton and Sanders in '16.  (Please correct me if I'm wrong.)  This stands in contrast to 2004, when we saw the Dean vs. Gephardt brawl, which boomberanged on them and paved the way for Kerry and Edwards finishing 1 and 2 in Iowa.

Will we see negative TV ads in the primary this time?  And if so, which candidate is the most likely to fire first, and against whom?

[Progressive Pessimist]

Not directed at specific candidates, but I fully expect some ads deriding the ideas and policies of other candidates whether it be from a more idealistic perspective or a more pragmatic one, and anyone who isn't an idiot can probably piece together which candidates those ads are referring to.