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 letter notes: where there’s a will, there’s a way. And there’s certainly the will.

Congressional leaders and the Obama transition team are already consulting closely on a massive economic stimulus package, to be enacted soon after President-elect Obama takes the oath of office. A major component of the package will be investments to repower America with clean energy. According to a New York Times article, a senior Obama aide said the package will include at least $15 billion dollars a year — and perhaps considerably more — for expanding mass transit, making American homes more energy efficient, and jumpstarting clean energy projects. The measure would reduce U.S. global warming emissions while also improving U.S. energy security and creating several million new green jobs.

The economic stimulus package is the first order of business. Broader energy and climate legislation comes next. President-elect Obama has said he’ll begin immediately working with congressional leaders to craft a strong climate bill. A recent Zogby poll found a strong majority of voters want Congress and the president to prioritize action on climate change.

Senator John Kerry (D-Mass.), the incoming chairman of the U.S. Senate Foreign Relations Committee, has signaled that the new Congress will work closely with the Obama administration to make rapid progress on global warming, both at home and abroad. He will bring this message to Poznan later this week, where he’ll tell the world that the Congress joins President-elect Obama in committing to re-engage with the international community to reach agreement in Copenhagen.

With support from the public and Congress, President-elect Obama stands on the edge of a new age of American leadership on the global stage, and he appears ready for the challenge. And that’s a game changer.