What was one of the best reasons that resentment toward Abraham Lincoln built up to an assassination attempt?

Removal of slavery from the country and defeat of confederate army.

Explanation:

The rules and laws of removal of slavery from the country and defeat of confederate army are the reasons that display resentment toward Abraham Lincoln which leads to an assassination attempt. Slavery is a big issue in the United states, the southern states want to maintain slavery whereas the northern states wants to end slavery which leads to civil war. Due to defeat of southern states in the war, the supporter of confederate army attempt assassination on Abraham Lincoln.

wait history, who want to talk about history, boring.

the roman empire began to fall