What was ironic about foe in the election of 1864?

In the 1864 presidential election, the incumbent President Abraham Lincoln ran against Democratic nominee General George B. McClellan. Despite facing the challenges of the ongoing Civil War, Lincoln secured a decisive victory. What was ironic about the election was that McClellan, who had served as the commanding general of the Union Army at the beginning of the war, had been replaced by Lincoln due to his perceived failures. As a result, it was ironic that Lincoln, the "outsider" who replaced McClellan, was able to defeat him in the election as the sitting president.