Democratic pollster Mark Penn writes the following:
Only two Democrats in the last 90 years have been reelected to a second term -- Franklin Roosevelt and Bill Clinton. The rest of the Democrats have seen their presidencies cut short, and so the historical odds of Obama winning a second term are at first glance not encouraging. But I do believe President Obama can overcome those odds and win reelection if he takes the right road.
This is a silly way to look at the odds of Obama being re-elected. Penn is collapsing the distinction between FDR's three re-election victories and subsequent presidents, who have only been re-elected once at most. If we consider the full set of cases from the last ninety years in which elected Democratic presidents were alive and eligible for re-election, the "historical odds" are far more favorable to Obama than Penn suggests:
FDR 1936 - re-elected
FDR 1940 - re-elected
FDR 1944 - re-elected
Truman 1952 - did not run
LBJ 1968 - did not run
Carter 1980 - defeated
Clinton 1996 - re-elected
If we count the cases where the incumbent did not run as defeats, the Democrat was re-elected in four out of seven cases. By this standard, Obama has a better than even chance. And if we count Democratic vice presidential successors who were already president but ran for the first time at the top of the ticket (Truman in 1948 and LBJ in 1964), then the odds are even better: 6/9.
Compare the Democratic track record for presidents seeking re-election to the Republican one during this time period:
Coolidge 1928 - did not run
Hoover 1932 - defeated
Eisenhower 1956 - re-elected
Nixon 1972 - re-elected
Reagan 1984 - re-elected
Bush 1992 - defeated
Bush 2004 - re-elected
The odds are four out of seven - identical to the Democratic number. If we include vice presidential successors who were already president running for election the first time (Coolidge in 1924 and Ford in 1976), the odds are again identical to the comparable Democratic figure: 6/9.
In short, if we properly account for FDR's three victories, there's no difference in re-election performance between the parties. Republicans have had more individuals get re-elected during this period (especially in the recent past), but the data don't support the claim that the "historical odds" are against Obama.
In his post, Penn goes on to offer advice and analysis on how to "overcome" the supposedly unfavorable odds Obama faces based on his experience as an adviser to Bill Clinton's 1996 campaign. In reality, however, the primary factor that will determine whether Obama is re-elected is the state of the economy, not campaign tactics or the historical performance of previous Democratic candidates.