General McClellan was removed from his position as commander in response to the President's concern about the slow pace of the Union troops under his direction. He seemed unable to muster the courage to aggressively engage Confederate General Robert E. Lee's Army of Northern Virginia. McClellan responded "You may find those who will go faster than I, Mr. President; but it is very doubtful if you will find many who will go further."
In a letter sent by the former first lady, Mary Todd Lincoln, she advised her husband to remove McClellan from the command. Whether she influenced the President’s decision is unknown. Lincoln named General Ambrose Burnside to be the new commander of the Army of the Potomac on November 5, 1862.
After his removal, McClellan battled with his old boss for the presidency in 1864 but was easily defeated.
In the Obamacare war, Ted Cruz was said to be Grant and Karl Rove was compared to General George B. McClellan, the man who built the Army of the Potomac. Read more at Examiner.com.