The chairman of the Senate Energy and Natural Resources Committee, Senator Jeff Bingaman, and his staff have been in discussions with the White House for almost two months on the clean energy standard legislation.
Bingaman and the top Republican on the energy panel, Senator Lisa Murkowski, issued a "white paper" seeking comment from the public on what the clean energy standard should look like.
While the president said he wanted to include nuclear power in the standard, Bingaman and Murkowski asked in their white paper what energy sources should qualify as clean energy, and if Japan's nuclear crisis "may affect the potential growth" in the U.S. nuclear generating capacity.
It's fairly unusual for legislation to be written this way, especially for something that is a top priority of the White House.
A Bingaman aide stressed the white paper did not mean the bill was in trouble. "We're just trying to make sure that enough members of the committee to pass the bill out are on board and agree that we have it structured properly," the aide said.
The lawmakers also asked if all electric utilities should be subject to a clean energy standard.
They noted that in similar legislation passed by the Senate energy committee in the last Congress, only utilities selling more than four million megawatt hours of power in a calendar year would be subject to a clean energy mandate. Obama's plan doesn't have such a threshold.
In addition, Hawaii was exempted from the Senate bill that required utilities to generate 15 percent of their power from renewable energy sources, like solar and wind, by 2021. Obama did not mention excluding any states from his plan.