Uganda, Feb. 12 -- More than ever before, Americans are dissatisfied with their two main political parties, the Democrats and the Republicans. In a recent Gallup poll, 63 percent of respondents - the highest percentage ever - said 'a major third party is needed.

Yet with voters so polarised, America's conventional first-past-the-post electoral system (each voter casts a ballot for a single candidate, and the candidate with the most ballots wins) prevents a third-party candidate from posing a serious challenge, even if he or she can bridge ideological divides.

Democratic voters may greatly prefer a third-party candidate to the Republican, but they will still cast their ballot for the Democrat given their strong partisan preferences; Repu...