On the GOP side, only T. Cruz and D. Trump have a mathematical chance to secure the nomination prior to the convention.

Cruz, so far, has earned 406 of a possible 1398 delegates (29.1%) and would have to earn 831 of the remaining 1079 (77%) to secure the nomination at large.

Trump, so far, has earned 661 of a possible 1398 delegates (47.3%) and would have to earn 676 of the remaining 1079 (62.7%) to secure the nomination at large.


Given that Cruz would have to, essentially, triple his delegate earnings, it is unlikely that he can secure the nomination prior to the convention even if he runs the table and wins all remaining states. The remaining proportional primaries effectively render his outright win impossible even if he were to win every winner-take-all contest remaining.

Trump has a better shot. Much will depend on Rubio supporters and where they migrate with him out of the race. If they go for Kasich or Cruz in large part (regardless of combination) then this will go to the convention. If a large bloc of them shift to Trump, giving him bigger proportional victories and more wins in the winter-take-all category, it is possible that a sense of "inevitability" will suppress non-Trump votes and allow him to squeak out enough delegates for an at large win. However, the more likely result sees Trump earning about 55% of the remaining delegates and falling short by about 80-100 delegates.

Thus, we are likely to see the first "contested" convention in the USA since Adlai Stevenson, on the third convention ballot, secured the chance to lose to Eisenhower in 1952.

Historically, contested convention candidates for the Democrats have fared really poorly against their opponents with about a 30% win rate -- including the era when contested conventions were more the "norm." By contrast, the win/loss rate for Republican candidates following a contested convention has been much closer to the success rate of an at-large republican nominee. This is because, traditionally, the GOP has always been the more organized and unified party -- something that is decidedly NOT in evidence this year after a decade of TEA party internal opposition.

It is likely to be an 'interesting' electoral year (but remember, the Chinese use 'interesting' as a curse).