Elections: 1844-1852

John Tyler was a one term incumbent president without a party. The former Democrat turned Whig was abandoned by his party when he started vetoing bills sent to him from Whig leader Henry Clay. Tyler's cabinet resigned in protest and the Whigs nominated Henry Clay for the presidency in 1842.
The Democrats were not as united as the Whigs. At their convention, it took eight ballots to come up with James K Polk. Martin Van Buren had been the early leader, but he could not get enough delegates for the nomination. The party turned to Polk as a compromise that everyone could settle on.
The election of 1844 was very close. Polk edged Clay 50%-48%. Democrats united against Clay. They hated him almost as much as today's Democrats hate W. In New York, abolitionist James Birney siphoned away enough votes to ensure Polk captured the state. Without Birney, Clay probably wins New York and the election. Instead, he's a three time loser.
In 1848, Polk stepped down after a successful term in office. The Democrats nominated Lewis Cass of Michigan while the Whigs nominated General Zachary Taylor. The main issue was slavery in the territory captured during the Mexican War. Taylor did not speak on any issue. Since he was a Louisiana slaveholder, the South did not have one of their hissy fits, and found him acceptable.
The slave holding war hero Taylor was not the only problem for Democrats. They also had to deal with Martin Van Buren. The former Democratic president decided to run as a third party candidate with the Free Soil Party. This is the equivalent of Al Gore running with the Green Party today. With Democrats Cass and Van Buren in the race, Taylor won with 47%. A united Democratic Party probably wins this election.
Zachary Taylor died in office and the Whigs did not want to nominate the boring President Millard Fillmore in 1852. Instead, they went the general route again. This time, they nominated Old Fuss and Feathers, Winfield Scott. Scott was the worst candidate in presidential history. He managed to insult just about everyone while looking inept.
Meanwhile, the Dems also nominated a Mexican War vet. Franklin Pierce got the Democratic nomination for two reasons. First, he was a veteran which countered Scott somewhat. Second, he was offensive to no one in the party. The country was beginning to splinter on the slavery issue and Pierce was a likeable fellow. At this point, Pierce was liked by all and offensive to none. Franklin Pierce wins the election 51%-44%. Pierce would go on to have a very gloomy presidency and even gloomier life while Scott would lead the army in the early days of the Civil War before being forced into retirement.