The new ABC News/Washington Post poll shows that Barack Obama has a nine-point lead over John McCain among "likely" voters, 52% - 43%. This cannot be good news for the McCain campaign.

However, a closer look at the poll's internals shows that the poll's respondents self-identified 54% Dem and 38% Repub -- a sixteen-point advantage for the Dems among registered voters.

For some historical perspective on this, only three Democratic Party candidates have won by more than 10% points since the Civil War: FDR won by 17.8% and 24.3% in 1932 and 1936; and LBJ won by 22.5% in 1964.

Prior to the Civil War, Andrew Jackson won by 17.8% in 1832.

In more recent history, the Dems won the 2006 aggregate US House vote by 7.9%. Since 1942, the Dems have won the aggregate House vote by more than 14% only twice: in 1974 by 16.6% and in 1964 by 14.5%.

Add to all of this the fact that only four Democratic Party presidential candidates have ever achieved a real majority since the Civil War (for a total of seven times: Samuel Tilden in 1876; FDR in 1932, 1936, 1940, and 1944; LBJ in 1964; and Jimmy Carter in 1976).

Looking at all of this historical data, a 16-point spread in party ID is pretty bold assumption made by the ABC News/Washington Post pollsters.

How do they justify it?

Update: Ed Morrissey has more thoughts.