HISTORICAL EFFECT OF MSM BIASING POLLS:
None, or it may actually hurt them.
The best place to look at MSM biasing of polling is the NYTimes polling of the Reagan/Carter race. Prior to the election, NYTimes had Carter ahead in most battleground states. Result, he was beaten, badly.
So does the biasing of MSM polling have a "self-fulfilling prophecy" effect? Apparently not. As a matter of fact, due to the MSM credibility boomerang, it may actually hurt the Democrats chances by:
- pissing off Republicans and Independents.
- making Democrats overconfident.
No one has every won the White House without taking over 50% of the Independent vote.