Jonathan Rauch says that:
Now is therefore as good a time as any to jump to a conclusion: the question history will ask is whether Bush's presidency was as bad as Richard Nixon's or only as bad as Jimmy Carter's.
For the disenchanted--again, including me--the relevant points of reference now are not Churchill or Truman but Nixon and Carter.
Is there no middle ground between Truman and Carter? Maybe an Eisenhower or Woodrow Wilson?
Rauch says there are four things that will lead to Bush being compared to Carter and Nixon: the fiscal mess, the Iraq mess, international opprobrium (i.e., the international community doesn't like us), and the extralegal terrorism war (i.e., wiretapping).
I'll largely concede the fiscal mess, although Bush might still get some relief on that one if the deficit keeps heading in the direction it currently is.