The top Republican on the Senate Energy and Natural Resources Committee, Domenici's opinion carries significant weight on energy matters, and during the last week, he waged a campaign to defeat the measure if it included the tax provision and renewable mandate for utilities.
The day's other leading performers included BT - up 2.6% - and United Utilities, which rose 2.5% after an upgrade of the sector by Goldman Sachs and recent excitement surrounding the overseas bid interest in rival Severn Trent.
It tried to force utilities to increase production of renewable energy in the face of fierce opposition by the utility industry group, and it included a tax package that the White House has long indicated it would not support.