“If they are that worried about competition from third party candidates, rather than trying to limit voters’ choices, politicians should implement Instant Runoff Voting, which would allow voters to rank their candidates in order of preference, end the ’spoiler problem,’ and allow people to vote their conscience without helping to elect the major party candidate they like least.”

IRV does not eliminate the spoiler effect. Here’s a simple example:
http://rangevoting.org/CoreSupp.html

IRV does not make it “safe” for voters to always support their favorite candidates.
http://rangevoting.org/TarrIrv.html

Third parties must support Score Voting (aka Range Voting), especially if you want to break the two-party strange-hold that prevents us from implementing proportional representation. Here is a letter to CFER about this:
http://rangevoting.org/CFERlet.html

Clay Shentrup
San Francisco, CA
206.801.0484
clay@electopia.org