It's a basic fact of politics that partisans of both sides always think their party compromises more readily than the other party. At the same time, I think it is the case that, though Democrats overstate their own party's tactical weakness, Democratic leaders really are more probe to compromise than Republican leaders. One reason is that Republicans are a homogeneous conservative party, while Democrats are a heterodox mix of moderates and liberals. Another reason is that, on economic issues, Republicans have a homogeneous business base, where Democrats must try to balance between business, labor and consumer or environmental groups.
And a new Gallup poll shows a third reason -- liberals just plain like compromise more than conservatives do:
It's not actually such a surprising result. In foreign, domestic and social policy, conservatism tends to represent aggressive promotion of self-interest, while liberalism stands more for balancing out others' interests alongside your own. It's pretty interesting to see that borne out so starkly in terms of the two sides' approach to politics.