SOPA could be used to censor candidates: 
Increasing Political Opposition to SOPA
SOPA Enables Net Censorship
Internet Censor Bill to Target Political Blog WebsitesCongress’s Piracy Blacklist Plan: A Cure Worse than the Disease?
Preliminary Thoughts on Stop Online Piracy Act (SOPA)
SOPA: An Architecture for Censorship
Senators Rand Paul, Jerry Moran And Maria Cantwell All Warn That PROTECT IP Will Kill Jobs
Strange bedfellows: Nancy Pelosi, Ron Paul join SOPA opposition
Issa: Congress using Google as ‘piñata’
Altering how the Internet works but not understanding it
House members unveil Stop Online Piracy Act
Go Daddy Reverses Position on SOPA, Yanks Support
‘Anonymous’ Blacks Out the Internet in Response to SOPA Debate
SOPA Won’t Stop Online Piracy, Would Censor Everyone Else
Stopping SOPA
Online Piracy and SOPA: Beware of Unintended Consequences