Senator William Henry Seward of New York was the front runner in delegates at the Republican National Convention in 1860, but Abraham Lincoln won the nomination on the 3rd ballot, and went on to become the greatest President in American history!
Speaker of the House Champ Clark of Missouri was the front runner in delegates at the Democratic National Convention in 1912, but Woodrow Wilson won the nomination on the 46th ballot, and went on to become one of the most significant President in American history, and took us through World War I.
Former President Martin Van Buren of New York was the front runner in delegates at the Democratic National Convention in 1844, but James K. Polk won the nomination on the 9th ballot, and went on to gain more territory, by peace treaty with Great Britain and war with Mexico, than any President except Thomas Jefferson!
Seward went on to become Lincoln’s and Andrew Johnson’s Secretary of State, and helped to prevent Great Britain or France from recognizing the Confederate States of America during the Civil War, and was able to arrange the purchase of Alaska from Czarist Russia in 1867.
Champ Clark remained Speaker of the House, and served eight years, from 1911-1919, one of the longer lasting Speakers in American history, with only five Speakers serving longer than him.
Martin Van Buren could have been the first Grover Cleveland, to have served two non-consecutive terms in the White House, but instead ran for President once again in 1848 as the candidate of the Free Soil Party, and in so doing, undermined the Democratic Party nominee, and helped indirectly to elect Whig nominee Zachary Taylor. Van Buren became the first former President to run on a third party line, and the Free Soil Party was the first significant third party, winning 10 percent of the national popular vote, and being a forerunner of the modern Republican Party, which formed six years later, in 1854.
A total of nine times in American history, we have seen the front runner in delegates fail to win the party’s nomination–three times for the Democrats, five times for the Republicans, and once for the Whigs, so if Donald Trump were to be denied the Republican nomination in 2016, it would be far from unique or unusual!