Answers to Ustwo's questions.
1) Republicans
2) Kerry and GWBush '00 are both slamming GWBush '04 actually.
3)
Both, Though overwhelmingly Republican in party donations.
Some Republicans are letting it expire and many Democrats are happy with this as well. If there was a concerted effort by the Democrats to bring this to a vote I guarantee you would find a sizeable majority voting in favor of the ban, and Bush's signature.
Hell, Even the conservative messiah, Ronald Reagan
Supported the Assault Weapons Ban in 1994
Not just that,
he lobbied for the law.
Lebell, I think we would all be surprised to see where people really lay on this issue. Many who are personally against it might only vote for it because of recent polling that 71% of americans are in favor of it's continuation. Other than that I don't think there is any real difference between the parties outside of the more bombastic leaders.