NASHVILLE, Tenn. (AP) — Barack Obama and John McCain clashed repeatedly over the causes and cures for the worst economic crisis in 80 years Tuesday night in a debate in which Republican McCain called for a sweeping $300 billion program to shield homeowners from mortgage foreclosure. “It’s my proposal. It’s not Sen. Obama’s proposal,” McCain said at the outset of a debate he hoped could revive his fortunes in a presidential race trending toward his rival. In one pointed confrontation on foreign policy, Obama bluntly challenged McCain’s steadiness. “This is a guy who sang bomb, bomb, bomb Iran, who called for the annihilation of North Korea — that I don’t think is an example of speaking softly.” —-Contact The Daily Reveille’s news staff at [email protected]