A top Republican lawmaker said Sunday that America must explore alternate energy sources to avoid being held hostage by Iran or by "wackos" in Venezuela -- an apparent reference to Hugo Chavez, Venezuela's populist president.

Sen. John McCain, a potential presidential contender in 2008, said recent action by "Mr. Chavez" and by Iran's leaders make it clear that the United States will be vulnerable as long as it remains dependent on foreign energy.

"We've got to get quickly on a track to energy independence from foreign oil, and that means, among other things, going back to nuclear power," McCain said on "FOX News Sunday."

"We better understand the vulnerabilities that our economy, and our very lives, have when we're dependent on Iranian mullahs and wackos in Venezuela," said McCain, who challenged President George W. Bush for the Republican presidential nomination in 2000.

Iran is OPEC's second-largest producer. Venezuela is the world's fifth-largest oil exporter, with the largest proven oil reserves outside of the Mideast.

Chavez, a frequent U.S. critic, accuses foreign oil companies of having looted Venezuela. He has promised that his socialist "revolution" is freeing the country from "imperialist" interests and restoring its sovereignty.