As Ford Showed In ‘76, Obama Had No Obligation To Defeated Candidate

Taken as a general matter, since the current primary-heavy process of selecting nominees began in 1972, victorious Presidential nominees have not selected their nearest rival in contested nomination fights as the Vice Presidential nominee.
Only twice in contested nomination battles beginning with 1972 has the Vice Presidential nominee been the second place finisher in total primary votes. The Democratic ticket in 2004 and the Republican slate in 1980 are the two.
The 2008 Democratic race was the closest in vote totals, but the ideological fight for the Republican nomination in 1976 (Convention photo above) may have been the more intense struggle.
In 2008, Barack Obama of Illinois and Hillary Clinton of New York each won just over 48% of the popular vote in the primaries with Mr. Obama winning a few more votes than Mrs. Clinton. For Republicans, John McCain of Arizona took around 45% of the total with Mitt Romney of Massachusetts and Mike Huckabee of Arkansas each in the low 20’s.
In going with Joe Biden of Delaware, Senator Obama has made his call. Senator McCain will do the same next week.
Here is some history on this matter—



