The Senate defeated an amendment for a two-year moratorium on earmarks in the food safety bill sponsored by Sen. Tom Coburn (R-Okla.) by a margin of 39-56. Eight Republicans voted against the ban, and seven Democrats voted for the ban.

The earmarks ban is a cause celebre for the tea party faction of the party, and the only Republican Senator who voted “no” on the ban facing a primary challenge in 2012 would be Sen. Richard Lugar (R-Ind.). Indiana tea party members were quoted in the New York Times and Politico last weekend saying a challenge to Lugar in 2012 is likely, especially after his advocacy for the START treaty with Russia on nuclear arms.

Olympia Snowe (R-Maine) and Kay Bailey Hutchinson (R-Texas) — who both may well face a 2012 tea party-led primary challenge — voted for the ban after voting against one in March. Democratic Sens. Claire McCaskill (D-Mo.) and Bill Nelson (D-Fla.) — two senators in Republican-leaning states up for reelection in 2012 — voted for the ban.

Even if the amendment did pass, it might not have become law anyway, as the food safety bill has to go to the House-Senate conference to work out differences between the two versions of the bill.