The DNC strategy was to amplify Trump because they thought he'd be an easy-lose candidate, and so they did.

http://www.salon.com/2016/11/09/the-hillary-clinton-campaign...

And the DNC/Clinton campaign worked closely with a number of outlets (like NYT) to publish various stories.

https://theintercept.com/2016/10/09/exclusive-new-email-leak...

This comes from the leaked e-mails, not hearsay.