Yes, before Obama even got elected the first time, a tape of him at a fundraiser praising a terrorist (Rashid Khalidi) made it's way to the
LA times office.
they never released it. Why? Obama's a democrat.
In this tape, Obama praises the PLO.
http://www.nationalreview.com/article/226104/la-times-suppresses-obamas-khalidi-bash-tape-andrew-c-mccarthy
This directly impacted the presidential race. Pretty sure it would have cost him a great deal of voters.
It's done all the time to republicans.