An earmark ban would be, at best, about one-millionth as important as conservatives make it out to be. Yet Mitch McConnell's fervent opposition is kind of strange:
Senate Minority Leader Mitch McConnell is maneuvering behind the scenes to defeat a conservative plan aimed at restricting earmarks, setting up a high-stakes showdown that pits the GOP leader and his “Old Bull” allies against Sen. Jim DeMint (R-S.C.) and a new breed of conservative senators.
In a series of one-on-one conversations with incoming and sitting senators, McConnell is encouraging his colleagues to keep an open mind and not to automatically side with DeMint, whose plan calls on Senate Republicans to unilaterally give up earmarks in the 112th Congress, according to several people familiar with the talks. ...
“My guess is that DeMint has the votes to push this through, but McConnell is whipping it hard,” said a Republican leadership aide, speaking on the condition of anonymity.
McConnell likes to deliver the pork, but it's not like he needs pork to keep winning easily. The only explanation I can think of is that McConnell, more than anything else, is an opponent of good-government reform. Opposition to campaign finance reform was the fight of his life, the cause that aroused the most genuine passion in him. He just loathes the idea that reforms are needed to cleanse the government of corruption.
I don't think earmarks are a major cause of corruption and bad policy, but they are a cause. It's kind of fitting that this is one of the few conservative causes he opposes.