COSTA MESA, California (Reuters) - Only World War III would prompt Republican presidential candidate John McCain to bring back the military draft, McCain said on Tuesday.

Many Americans are fearful the U.S. government will be forced to reinstitute the draft given the prolonged Iraq and Afghanistan wars.

Asked about that possibility by a potential voter in Florida during a telephone “town hall meeting,” McCain said: “I don’t know what would make a draft happen unless we were in an all-out World War III.”

The United States ended its last military draft in 1973 in the waning years of the Vietnam war, moving to an all-volunteer military force.

McCain, a Vietnam veteran, said the draft during that conflict weighed most heavily on lower-income Americans, and that this should not be repeated.

“I do not believe the draft is even practicable or desirable,” McCain said.

(Reporting by Steve Holland, editing by Todd Eastham)