http://en.wikipedia.org/wiki/Voter_suppression

"Examples of voter suppression

2002 New Hampshire Senate election phone jamming scandal

In the 2002 New Hampshire Senate election phone jamming scandal, Republican officials attempted to reduce the number of Democratic voters by paying professional telemarketers in Idaho to make repeated hang-up calls to block Democrats' ride-to-the-polls phone lines on election day.
United States Senate election in Virginia, 2006

During the United States Senate election in Virginia, 2006, Secretary of the Virginia State Board of Elections Jean Jensen concluded that the incidents of voter suppression appeared widespread and deliberate. Documented incidents of voter suppression include:

* Democratic voters receiving calls incorrectly informing them voting will lead to arrest.
* Widespread calls fraudulently claiming to be "Webb Volunteers," falsely telling voters their voting location had changed.
* Fliers paid for by the Republican Party , stating "SKIP THIS ELECTION" caused was allegedly an attempt to suppress African-American turnout.

The FBI has since launched an investigation into the suppression attempts.
2004 presidential election

In the U.S. presidential election of 2004, some voters got phone calls with false information intended to keep them from voting--saying that their voting place had been changed or that voting would take place on Wednesday as well as on Tuesday.

Other allegations surfaced in several states that the group called Voters Outreach of America had collected and submitted Republican voter registration forms while inappropriately disposing of Democratic registration forms.

Michigan Republican state legislator John Pappageorge, was quoted as saying, "If we do not suppress the Detroit vote, we're going to have a tough time in this election."