Presidents considered the worst and most ineffectual are James Buchanan, Warren G. Harding and Andrew Johnson, states U.S. News & World Report. While Buchanan and Johnson bookend Abraham Lincoln, considered one of the best presidents, Harding spent less time governing and more time on personal pursuits.
Warren G. Harding, the 29th president, spent his time in the White House playing poker, golf and with his mistress. He left governing to his cabinet and his friends, as they took liberties without interference. He supported both the foes and proponents of joining the League of Nations. He ironically stated, "I am not fit for this office and should never have been here."
The 17th president, Andrew Johnson, took over for Abraham Lincoln following Lincoln's death. He refused to support Reconstruction policies that aimed to protect the rights of the newly freed African-American slaves, such as the 14th amendment to the Constitution. Congress impeached him during the power struggle, as he refused to support efforts to battle Southern policies that attempted to undermine the results of the Civil War.
The 15th President, James Buchanan, felt the growing crisis between the North and South would go away on its own. Against his own party, he recommended Kansas be admitted to the union as a slave state. He felt that the Supreme Court would decide once and for all the legality of slavery, and when they voted in favor of the Southern states in the Dred Scott case, he simply accepted the decision.