Claim: "An April study found that about 70 percent of ads in this election cycle have been negative , up from only 9 percent through the same period in 2008."
Fact-check: Sen. Sheldon Whitehouse of R.I. says growth of SuperPACs led to eightfold increase in negative campaign ads 
Verdict: mostly-true
Organisation: PolitiFact
Author: C. Eugene Emery Jr.
Date published: 2012-08-05T00:00:00