Why did harry Truman face a difficult reelect campaign in 1948?

Answer 1

He was unpopular throughout much of his first term, and the mid-term elections in 1946 were a disaster. The fringe of the Democratic Party, led by Henry Wallace, split, as they angry over Truman's foreign policy and Wallace launched his own campaign. Then during the Democratic National Convention, the large number of (racist) Southern Democratics, nicknamed the "Dixiecrats", walked out after Northern Democrats successfully managed to get the party to support Civil Rights. Their leader, Sen. Strom Thurmond, also launched a campaign, hoping to take away votes from the solidly Democratic South. Together, Thurmond and Wallace took 5% of the vote, while Truman won 5% more of the votes than Dewey.

All polls and pundits had predicted that Truman would lose; the economy and domestic politics had been in a mess throughout his presidency. By the time election day came, it seemed no-one believed Truman could win apart from Truman himself. Even his wife thought he would lose, yet he continue to tell everyone he met he knew he could win.

Answer 2

Southern Democrats were upset he supported civil right.