This morning I listened to an NPR segment that included a high level DoJ official from the Reagan administration. He was livid about Bush's signing statements, and explicitly stated that the practice abandoned core conservative values, most specifically (aside from plain matters of constitutionality), the recognition that however right one feels one's partisan cause, one cannot expect one's own angels to always occupy the office one now holds.
Sure. Some republican senators hint at similar opinions, but when push comes to shove they manage to find excuses to vote for the Bush position on legislation.
I heard similar comments before the 2004 election. Yet many of those critics managed to find was of voting for Bush anyway.
I still say they need to grow some spine.