In a letter from U.S. groups making the rounds here in Poznan, delegates are being urged to make the decisions needed in Poznan to keep us on schedule for making a final deal in Copenhagen next year, as promised in the historic consensus reached last December in Bali. While the December 2009 meeting in Copenhagen marks the deadline that nations -- including the United States -- have given themselves to reach agreement on a post-2012 climate treaty, a few observers have raised concerns that the United States might not be ready to cut a deal by then. But as the …