The election of Massachusetts State Sen. Scott Brown to the U.S. Senate changed the political and legislative landscape in Washington, D.C. like no political event in a generation. And even though the Democrats still control the presidency for at least three more years and both houses of Congress by healthy margins until the 2010 mid-term congressional elections, House and Senate leaders are re-tooling their entire legislative agendas with an urgency not seen on Capitol Hill in years. But the fact that one vote in the Senate could overturn an entire legislative agenda suggests that there may never have been strong consensus for President Barack H. Obama's ambitious green energy program in the first place.

The original energy/cap-and-trade legislative proposals were linked in the House of Representatives and passed by the narrowest of margins in June 2009. But even up to Mr. Brown's election on January 19, 2010, very little progress had been made in the Senate. Some of this was related to an overflowing legislative agenda in the Senate, including health reform, highway bill reauthorization, and the normal press of fiscal year 2010 authorization and appropriations bills. The Senate committees with jurisdiction over cap and trade and energy, Environment and Public Works, and Energy and Natural Resources, were booked all of 2009.

The cap-and-trade formulas were controversial, but elements of the supposedly less controversial energy bill, including the renewable energy standards (RES) also were controversial and remain so — now more than ever. There was never more than a one-or-two-vote margin in the Senate Energy Committee for the RES even before the election of Mr. Brown.

No one knows what this means for the green agenda. The dust has hardly settled on Mr. Brown's election — he hasn't even been sworn it yet. Even before Mr. Brown's victory in Massachusetts, some moderate Democratic senators had written off cap and trade, some as early as last fall. For instance, moderate Democratic Sen. Byron Dorgan (D-N.D.), a senior Democrat on the Senate Energy Committee, who recently announced his retirement in 2010, said the Senate would not consider climate change legislation in 2010.

Rather, Mr. Dorgan noted it would focus on the separate energy legislation that would include the RES that would require more electricity supplies to be generated from renewable sources, and expand offshore drilling into the eastern Gulf of Mexico. Mr. Dorgan said it would be difficult for the Senate to turn to controversial climate-change legislation after it just had to deal with the health care bill. That now seems to be an understatement given the Brown political tsunami. In many ways, cap and trade is more controversial than the health care debate, and for the general public, less understandable.

So where does it leave energy policy? It does remain a top priority for President Obama and Congress ? but there is now a serious question as to whether the bill will be as sweeping and transformational as it was once expected to be, or if it will be a bill more incremental in nature. Those doubts had been sown last fall, and the January 19 election brought them full circle.

In his State of the Union Address, President Obama did little to resolve this issue. He called on Congress, again, to enact the cap-and-trade bill along with the rest of his green agenda, but he also advocated the building of a new generation of nuclear power plants and renewed the debate concerning the opening up of new offshore areas to oil and gas development, two issues not previously part of President Obama's green energy initiative. He made these proposals in an effort to cross the aisle to foster a more bipartisan national energy policy. President Obama, however, provided few details about the nuclear or off-shore initiatives. It remains to be seen whether his plan will be bold enough to entice support from legislators who have been lukewarm to his energy proposal and in particular to his cap-and-trade proposal.

The coming days and weeks will determine whether the United States will take small incremental steps on energy or whether it will lead the world to a green future as the president's rhetoric trumpeted. As President Obama put it, "Do we want to be the dominant player in the future green world, or do we want to finish in second place?" Even the Republicans were applauding his statement that the United States does not finish second.