Washington Post: As the next round of U.N. climate talks approach this month in Cancun, Merxico, the Obama administration finds itself in an awkward position: pushing its enduring commitment to bold climate action even as the prospects for comprehensive legislation have evaporated at home. The atmosphere is very different from a year ago, when U.S. negotiators headed to Copenhagen touting the recent success of a House-passed climate bill. Now that legislation has died in the Senate, and with candidates poised…