Influential senators from both parties, backed by unions and some large electrical utilities, will unveil a new global warming proposal on Wednesday that could form the basis of a climate change compromise that has so far eluded Congress.

A U.S. Senate panel Wednesday began drawing up a sweeping law that would put mandatory caps on greenhouse gas emissions after a key Republican endorsed the idea.

The Senate's passage of an energy bill this week shows that elections matter -- even a slight Democratic majority, with the help of some Republicans, has begun shifting the nation's energy policy from a focus on drilling to conservation and using renewable fuels.