The 1864 Democratic candidate for President of the US was this former Union general.
Ambrose Burnside
John Pope
George McClellan
Joseph Hooker
George McClellan. McClellan had been relieved of command by President Abraham Lincoln for failing to pursue Lee’s army after the Battle of Antietam. During the 1864 campaign McClellan claimed the war was a failure and already lost. This was just eight months before Robert E. Lee surrendered the largest Confederate army to U.S. Grant.