Delaware was won by Democratic nominee Barack Obama with a 25.0% margin of victory, the best-ever result for a Democratic presidential candidate in Delaware as of 2020. Obama's large margin of victory was aided by his running mate, Joe Biden, a longtime U.S. senator from the state and the first Delawarean to appear on a national presidential ticket. At the same time, Biden was also running for a seventh term in the Senate, being elected during the same time he was elected vice president. During the campaign, Delaware was considered a safe blue state, and in the end only one county of Delaware's three counties, Sussex County, went for McCain, by a margin of approximately 7,000 votes or 8.58%.
Delaware was one of three states, along with rapidly left-trending Vermont and Obama's home state of Illinois, in which Obama outperformed Franklin D. Roosevelt in all four of his runs and Lyndon B. Johnson in his 1964 landslide.