From New York Magazine, via TPM:

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. Bush officials informed organizers of their intention to pull out of the new Kyoto deal late Thursday afternoon, soon after news leaked that Clinton was scheduled to speak, the source said. […] In his Friday speech, Clinton blasted the Bush administration’s opposition as “flat wrong.” But the speech almost didn’t happen. The contretemps started late Thursday afternoon, when the Associated Press ran a story saying that Clinton had been added at the last minute to the gathering’s speaking schedule at the request of conference organizers. According to the source, barely minutes after the news leaked, conference organizers called Clinton aides and told them that Bush-administration officials were displeased. “The organizers said the Bush people were threatening to pull out of the deal,” the source said. After some deliberation between Clinton and his aides, Clinton decided he wouldn’t speak, added the source: “President Clinton immediately said, ‘There’s no way that I’m gonna let petty politics get in the way of the deal. So I’m not gonna come.’ That’s the message [the Clinton people] sent back to the organizers.” But the organizers of the conference didn’t want to accept a Bush-administration dictum. They asked Clinton that he go ahead with the speech. “The organizers decided to call the administration’s bluff,” the source said. “They said, ‘We’re gonna push [the Bush people] back on this.'” Several hours went by, and at the Clinton Foundation’s holiday party on Thursday night, the former president and his aides still thought they weren’t going to Montreal. “The staff that was supposed to go with him had canceled their travel plans,” the source said. At around 8:30 p.m., organizers called Clinton aides and said that they’d successfully called the bluff of Bush officials, adding that Bush’s aides had backed off and indicated that Clinton’s appearance wouldn’t in fact have adverse diplomatic consequences.