Why did the Whigs choose not to renominate Millard Fillmore for president in the 1852 election?

The 1852 United States presidential election was the 17th quadrennial presidential election, held on Tuesday, November 2, 1852. Democrat Franklin Pierce, a former Senator from New Hampshire, defeated General Winfield Scott, the Whig nominee. This was the last election in which the Whigs served as the principal opposition to the Democrats.

Incumbent Whig President Millard Fillmore had acceded to the presidency after the death of President Zachary Taylor in 1850. Due to Fillmore's support of the Compromise of 1850 and his enforcement of the Fugitive Slave Law, he was popular in the South but opposed by many Northern Whigs. On the 53rd ballot of the 1852 Whig National Convention, Scott defeated Fillmore to clinch the party's nomination. The Democrats were divided among four major candidates, who traded leads through the first 48 ballots of the 1852 Democratic National Convention. On the 49th ballot, dark horse candidate Franklin Pierce won his party's nomination. The Free Soil Party, a third party opposed to the extension of slavery into the territories, nominated Senator John P. Hale of New Hampshire.

Explanation:

might be agreeing to participate ethically with other european nations in the slave trade

or notifying other european nations when taking possession   of african territories

oil! is what i am assuming