By offering an alternative view from within the same general camp, it has a better chance of giving judicious criticism that can be heard than do critical voices from outside. On the other hand, I think a great many evangelicals already feel more comfortable with the kind of views expressed by Jim Wallis and Tony Campolo than they do with a harder Right position. Wallis's and Campolo's appeal to moderation in politics is likely to be received more enthusiastically than their plea for economic and personal simplicity. You wrote about the independence of the leaders of the Religious Right. An enduring characteristic of fundamentalism is its vulnerability to a sectarian spirit.
Sectarianism is almost by definition fissiparous.
Those quite human and understandable characteristics exist in any kind of organization. But they are exacerbated in organizations which have people of great zeal and conviction. Many of the leaders of the Religious Right are broadcasters. One of the things we've learned over the last 15 years is that while the audience for religious broadcasting is quite substantial, it's also finite. People are going after the same audience.