So, for example, paradocs had a great suggestion, seconded with some modification by Paul Rosenberg, that began with:

But of course Bush has claimed it wasn't illegal, and even inasmuch as that might seem self-evident to us, chances are that many people believe him.  I.e., it's part of the controversy.  So, a more neutral way to phrase it would be something like:

[...]obtaining a court warrant.  President Bush has argued that he has the legal authority to do this, and that he has carefully monitored the program to preserve civil liberties.  Critics have argued that this violates federal law and prohibitions in the United States Constitution, and sidesteps the U.S. Congress.

Or some variant; then ask if people think it was illegal.  This may be too long, and I'm not so much concerned with the specific example -- the point is that fine-grained edits will be incredibly important throughout the poll, to make sure they are as unimpeachably neutral as possible.  Otherwise, the results will be too easily ignored by MSM editorial staff.  Morin's assertion that even mentioning impeachment is biasing demonstrates what kind of a hurdle we have to jump over; squeaky-clean is going to need to be the rule.