Garry Wills explains why this whole notion of getting our elected officials to sign "pledges" is a bad one.
Somewhere on the 'net, I read (but forgot to bookmark or link to) an article that explained why the Grover Norquist "I will never raise taxes for any reason, even if you're about to detonate a nuclear weapon in Pittsburgh" pledge actually contributed to higher taxation. It had to do with taking off the table a small tax increase in one area that would lead to a large tax cut in another…or with not paying off debts which, as any credit card holder knows, are sometimes prudent to pay off.
If I were Jon Stewart, I think I'd send my correspondents around Washington and try to get as many lawmakers (or candidates for those positions) as possible to sign a pledge not to sign pledges.