From New York Magazine:

Bush-administration officials privately threatened organizers of the U.N. Climate Change Conference, telling them that any chance there might’ve been for the United States to sign on to the Kyoto global-warming protocol would be scuttled if they allowed Bill Clinton to speak at the gathering today in Montreal, according to a source involved with the negotiations who spoke to New York Magazine on condition of anonymity

They eventually backed down when the conference organizers decided to “call their bluff.” Seems a bit petty, don’t ya think?

(found via TPM)