Actually, not that new. Clinton did it in 1995:

One veteran Democratic operative, who blames overheated rhetoric for the shooting, said President Barack Obama should carefully but forcefully do what his predecessor did.

“They need to deftly pin this on the tea partiers,” said the Democrat. “Just like the Clinton White House deftly pinned the Oklahoma City bombing on the militia and anti-government people.”

It should be note again and again that there is absolutely no evidence that this wacko had any connection, directly or indirectly, to tea partiers. And the Pima County Sheriff acted in a most irresponsible manner yesterday to jump to that conclusion.