JACKSON, Miss. (AP) — Mitt Romney may still be fighting to win the Republican presidential nomination, but he's also been fielding questions about who he'd choose as his running mate.The question came up again Friday during a town-hall meeting in Jackson, Miss. While Romney offered no names, he says the Republican Party has many excellent governors, senators and former elected officials.He said his most important criteria in a running mate would be a person who has shown they can be president.Romney leads his Republican rivals in the race for convention delegates as the party's nominating contest turns to the Deep South. The former Massachusetts governor was headed to Alabama after his Mississippi stop. Both states hold GOP primaries on Tuesday.