The reason tea parties are enjoying success, over half the country agrees with the parties core principles; deficit control and smaller government.
Tea parties seem to be populated by the extreme fringe of the Republican Party and self described independents - neither population seems to understand compromise or the process of law making.
Half the country does agree with the principles of deficit control and less government, and at least half of that half are moderate Democrats. The other half does not include Bush&Co, if their actions are any indicaton of their ideals.
Moderate Republicans and moderate Democrats - the majority of Americans I believe - support limited government, and the principles of governance outlined in the Preamble to our Constitution.