I have finally found something interesting on Wikileaks. Here is the 2008 Atlas project report on how to rig polls: https://wikileaks.org/podesta-emails//fileid/26551/7326
The strategy is really simple: oversampling Hispanics, Native Americans and African Americans: http://www.zerohedge.com/news/2016-10-2 ... versamples
There is even evidence that strategies like these have been used to rig the polls.
According to CNN (Crooked News Network) Hillary Clinton was leading over Trump with a margin of 5: http://edition.cnn.com/2016/10/19/polit ... p-by-five/
Nobody will actually read the 19 October poll by Cronkite (Crooked) News: https://cronkitenews.azpbs.org/2016/10/ ... poll-data/
Or they would see that they simply oversampled Democrats – 413 against only 168 Republicans (but the margin was only 5!). Check out one of the tables from this report.

Reuters rigged the polls from October 25: 43% Democrat against 35% Republican - http://www.realclearpolitics.com/docs/2 ... 5_.16_.pdf

AP rigged another October poll (37% Democrat, 25% Republican): http://ap-gfkpoll.com/main/wp-content/u ... mpaign.pdf

But some might argue that rigging polls is not yet rigging elections.
The strategy is really simple: purge selected voters to prevent them from voting and manipulate the voting machines so votes in the districts where you expect the majority voting against the preferred candidate are rejected. This has been done before, for example in the presidential election of George Bush in 2000. See the following quote from another thread.
Firestarter wrote:I recommend Palast’s book The Best democracy money can buy (2002): http://www.chemtrails911.com/books/The% ... ast%20.pdf
(...)
STEALING FLORIDA ELECTION 2001 – GOVERNOR JEB BUSH
Palast dedicates some pages in his book to how the presidential elections of 2001 were stolen by George W. Bush, with the help of the governor of Florida, Jeb Bush (George’s younger brother)
Where Bush officially won with a margin of 537 votes, Palast explains tens of thousands of voters were illegally prevented from voting, , most of which would have voted Al Gore for president. Greg Palast estimates that 52,000 voters were removed in Florida, because they were erroneously considered “criminals” without the right to vote.
ChoicePoint DBT was the company that purged “criminals” from the voting list. One of the tricks was to purge anybody with a 90% name match (for example: “Anderson” would make “Andersen” lose his vote). 179,855 ballots were simply not counted, depending on skin colour. For example: in Leon (a “White” county) one in 500 ballots was “spoiled”, while in neighbouring Gadsden, (with a high percentage Black) one in eight ballots was rejected.
Since George Bush junior became inaugurated as president: Colorado, Indiana, South Dakota, Texas, Virginia, Georgia, Kansas, Montana and Washington have passed laws that cleanse voter rolls in a similar (illegal) way as Florida did in 2001..