"A dark horse," is one that shows unexpected racing speed and comes in first, even though the experts said he had little chance of winning. In politics, an unknown candidate for office who wins a nomination or election is called "a dark horse". British Prime Minister Benjamin Disraeli is believed to have been the first to use the phrase. In his novel, The Young Duke, published in 1831, Disraeli described a horse race and told how the two top choices fell behind, while "a dark horse which had never been thought of came in first in a sweeping triumph." As a political phrase, "dark horse" appeared for the first time in the national Democratic Party convention of 1844. The "dark horse" was James Knox Polk, who became the 11th President of the United States. As a national leader, he was considered a political nobody. Nevertheless, he surprisingly won the Democratic nomination and was elected President. This is what happened: Martin Van Buren of New York, a former President, seemed sure of getting the nomination. But he opposed making the territory of Texas part of the United States, as another state. He was against it because there was slavery in Texas. Van Buren did not want another slave state in the Union. As a result, he lost support among those Democrats who supported slavery. At the 1844 convention, Van Buren could not get enough votes to win the nomination. The convention was deadlocked. Therefore, the Democratic leaders decided that the only wise thing would be to run a "dark horse", a man who could unite the party. And so, one of the party leaders, George Bancroft, proposed the name of James Knox Polk. He won the nomination and election.