Third Party Presidential Candidates

Republicans have some concern that after Ron Paul fails to win the Republican nomination for president he will run for president as a Libertarian. And of course in 2000 Pat Buchanan did run for President as a non-Republican after he lost the parties' nomination.

What the Republican party should have done is ask all candidates for President to sign a pledge promising "on their honor as Americans" not to run for President should they not win the nomination. To compel everyone to take the pledge, the signing candidates should refuse to participate in any debate that contains a non-signing candidate.