A group of high-profile liberal activists, including authors Howard Zinn and Gore Vidal, filmmaker Robert Greenwald and Eli Pariser, one of the leaders of MoveOn.org, have written an open letter to Barack Obama, criticizing what they call "troubling signs that you are moving away from the core commitments shared by many who have supported your campaign" and urging him to "stand firm on the principles you have so compellingly articulated."

"We recognize that compromise is necessary in any democracy. We understand that the pressures brought to bear on those seeking the highest office are intense," the group of more than two dozen intellectuals and activists wrote in a letter posted on the website of The Nation magazine on July 30. "But retreating from the stands that have been the signature of your campaign will weaken the movement whose vigorous backing you need in order to win and then deliver the change you have promised."

The group specifically criticized Obama for his vote for a bill that granted telecommunication companies immunity from prosecution for a controversial Bush administration domestic wiretapping program. They called on Obama to remain committed to goals he has set, such as universal health care and removing troops from Iraq on a timetable.

Such a small core of activists don't post much of a political problem for Obama, who is popular among voters who identify themselves as liberal.

But this group previewed some issues where they would challenge Obama if he wins in November.

"In other areas--such as the use of residual forces and mercenary troops in Iraq, the escalation of the US military presence in Afghanistan, the resolution of the Israel-Palestine conflict, and the death penalty--your stated positions have consistently varied from the positions held by many of us, the 'friends on the left' you addressed in recent remarks," they wrote. "If you win in November, we will work to support your stands when we agree with you and to challenge them when we don't. We look forward to an ongoing and constructive dialogue with you when you are elected President."

The letter adapted Obama's own slogan "Change We Can Believe In," with special emphasis on the word "we." It was also signed by author Walter Mosley and Katrina Vanden Heuvel, editor of The Nation.

By Perry Bacon, The Washington Post, August 5, 2008