We lowered our long-term rating on the U.S. because we believe that the
prolonged controversy over raising the statutory debt ceiling and the related
fiscal policy debate indicate that further near-term progress containing the
growth in public spending, especially on entitlements, or on reaching an
agreement on raising revenues is less likely than we previously assumed and
will remain a contentious and fitful process. - S&P Analysis
Ahh it wont allow me to link to the standard and poors site that has the entire article because I dont have 15 posts as of yet :{ Above is an actual excerpt.
No, its not just the Tea Party, though they are part of it. It is because of the intractability of the entire political process, of which the Tea Party are a part.
S&P downgraded us because of politics, not because of economics. They aren't saying we can't pay or make sacrifices. They are saying we aren't willing to pay or make sacrifices.