Apparently, the Senate voted earlier this year on whether or not to impose an earmark moratorium for 2010 and 2011. The measure was tabled with 68 senators supporting tabling the moratorium and 29 senators in support of moving towards a vote. This means that 68 senators opposed the moratorium and 29 supported it.
Here are the Republicans who voted against an earmark moratorium who will continue to serve in the 112th Congress, and thus have a vote on the caucus earmark moratorium:
Lamar Alexander Thad Cochran Susan Collins Kay Bailey Hutchison Jim Inhofe Richard Lugar Lisa Murkowski Pat Roberts Richard Shelby Roger Wicker
It's likely that McConnell would have the votes to impose a caucus-wide earmark moratorium, which would, of course, only be bound by how much individual senators cared about bucking their party leader.