Hyperbole refers to the use of exaggerated language. Sometimes a person can influence us to believe a claim simply by overstating it. While we aren't likely to believe the exaggerated claim taken literally, the fact that someone is willing to state their view so powerfully can subtly make us think they must be onto something.
Example #1:
In this campaign ad endorsed by Romney, the narrator refers to Obama's view that coal-burning factories should be heavily taxed for pollutants as Obama's "War on Coal." Clearly, it is an exaggeration to say that Obama is engaging in "war," but the use of such exagarated language might well lead us to think that Obama's policy on coal pollution is unfair even without having critically examined it.
Example #1:
In this campaign ad endorsed by Romney, the narrator refers to Obama's view that coal-burning factories should be heavily taxed for pollutants as Obama's "War on Coal." Clearly, it is an exaggeration to say that Obama is engaging in "war," but the use of such exagarated language might well lead us to think that Obama's policy on coal pollution is unfair even without having critically examined it.
Example #2:
Here Romney claims the Obama has "piled on mounds of record-breaking regulation and bureaucracy." It would probably be controversial enough to say that Obama has imposed a record-breaking regulation, not to mention a mound of record-breaking regulations, not to mention piles of mounds of record-breaking regulations. Thus Romney has overstated his point for rhetorical effect.