A large number of American liberals and left-wingers have signed an American version of the Euston Manifesto, dedicated to opposing Islamism, the violence and terrorism it has fomented, and the intolerance and illiberalism at its core. You can read the full text here. Money quote:
We are signers or supporters in the United States of the Euston Manifesto and its reassertion of liberal values. Our views range from those of centrists and independents to liberals of varying hues on to the democratic left. We include supporters of the decision to go to war in Iraq in 2003 as well as people who opposed this war from the beginning. However, we all welcome and are heartened by the decision of the writers of the Euston Manifesto in Britain to reassert and reinvigorate liberal values in the present context. Now we confront the issue of how to respond to radical Islamism. Some of us view this ideology and its political results as the third major form of totalitarian ideology of the last century, after fascism and Nazism, on the one hand, and Communism, on the other. Others regard it as having a history in the Arab and Islamic world that eludes the label of totalitarianism. We all agree however that it fosters dictatorship, terror, anti-Semitism and sexism of a most retrograde kind. We reject its subordination of politics to the dictates of religious fundamentalists as well as its contempt for the role of individual autonomy and rationality in politics, a rejection not seen on this scale in world politics since the 1940s. We understand that the United States must continue to take the lead with our allies in confronting this danger.