Nearly six years ago,  Senator John Kerry and Texas oil tycoon T. Boone Pickens were mortal political enemies.

As a major backer of President George W. Bush’s re-election effort in 2004, Pickens contributed millions to a right-wing ad campaign questioning Kerry’s record as a Vietnam war hero. The ads, which Kerry disputed, put him on the defensive and may have contributed to the Democrat’s failure to win the White House.

kerry_pickensOn Wednesday, the billionaire and the Massachusetts senator sat side-by-side in the Capitol’s ornate Senate Foreign Relations Committee room, where Kerry presides as its chairman.

Their mission: To spread the word about the legislation Kerry and Senator Joseph Lieberman have written to tackle global warming by reducing U.S. consumption of dirty-burning fossil fuels blamed for climate change.

“If you look at life looking backwards and standing in one place, you’re going to waste your time,” Kerry told a small group of reporters when asked about the new relationship with the man he now calls “Boone.” “Six years ago was six years ago,” Kerry said.