Washington ? Al Gore, the Democrats’ nominee for the White House in 2000, has all but ruled out running for president in 2008, saying the best use of his time is to educate people about global warming.

“I haven’t made a Sherman statement, but that’s not an effort to hold the door open. It’s more the internal shifting of gears,” said Gore, referring to Civil War-era general William Tecumseh Sherman. “I can’t imagine any circumstances in which I would become a candidate again. I’ve found other ways to serve. I’m enjoying them.”

Gore referred to Sherman’s famous words upon retiring from the Army in 1884 that put to rest talk of a presidential run: “If nominated I will not run; if elected I will not serve.”

Gore, in an interview broadcast Sunday on ABC’s “This Week,” stopped short of issuing such an equivocal statement. But he said his time is best spent educating people on heat-trapping gases raising the Earth’s surface temperature. He’s promoting “An Inconvenient Truth,” a film that chronicles his slide shows on global warming.