This may surprise you Geoff...
...but this is one "tree-hugger" who is not necessarily opposed to nuclear power.
As for Congress...it has never had the opportunity to consider the full Protocol. In 1997, the U.S. voted unanimously against a single specific protocol relating a waiver of participation for developing nations. But the entire treaty hadn't even been completed at the time. It was signed by Bill Clinton in November, 1998 and then summarily trashed by George Bush upon his ascendency to office.