Politico: GOP Conference Chairman Mike Pence is defending Republican use of a widely disputed cost estimate on a Democratic global warming proposal, even after an outcry from media, environmentalists, and climate change experts. “We are using the numbers that are in the public domain right now,’ said Pence (R-Ind.) in a Tuesday briefing with reporters. “Democrats have released no numbers.’ In speeches, interviews, and press releases, Republicans have repeatedly claimed that a cap and …