08/08/2007 at 06:00 PM EDT
traveled to 14 states in 2004 to stump for Democratic presidential hopeful Sen. John Kerry – but the actor and environmentalist isn't planning to campaign for any of the 2008 candidates just yet.
"I'm still on the fence about it, to tell you the truth," DiCaprio, 32, told reporters at Wednesday's press conference for The 11th Hour
in Beverly Hills. "I have yet to hear a candidate that has clearly laid out their environmental policy in a way that is inspiring to me."
The 11th Hour
is DiCaprio's new global-warming documentary, which he narrates and produces.
Sen. Kerry's candidacy prompted DiCaprio to become active in 2004's presidential campaign, the actor says: "I thought he had an amazing environmental policy. But I have yet to hear a candidate that has compared in that regard."
The Blood Diamond
star says he's looking for specifics from the 2008 candidates. "I'm waiting for the right questions to be asked, and for these candidates to give really clear responses to what they're going to do in a tangible way – not a lot of rhetoric," he said. "I want to hear hardcore facts."
But with the election still more than a year away, DiCaprio adds, "There is a lot of time left. ...I'm not sure what I'm going to do."
Some Hollywood stars have already declared support
for presidential candidates – at least financially. Campaign-donation records show Jennifer Aniston, George Clooney Halle Berry and Kelsey Grammer have all donated money to 2008 hopefuls.