A bit belated, but here's a link
to an article on the NRAILA website about the Senate letters to the Obama Administration expressing opposition to the ATT as it currently stands.
There are TWO letters, the one from Senator Moran (R - KA) mentioned above, with 45 signatories, and one from Senator Tester (D - MT), with 13.
I guess the Dems don't want to sign on to a Republican letter (they might seem bipartisan? Get cooties? I dunno...).
58 opposed... If this number doesn't change, due to defection, election, etc., the ATT will never pass.