Since losing the 2012 election, Mitt Romney has made many comments on current politics, often saying "he'd do a better job as President". Even criticizing the job of a potential candidate like Hilary Clinton, though after that he affirmed that he's not running again. I think most people who have gotten their party's nomination and lost don't stand a chance. Except maybe something rare like when Al Gore lost in 2000 (though he declined to run in 2004) with the popular vote win and the fiasco with the Supreme Court and Florida. The last person to be successful was Richard Nixon who originally lost to JFK. Though that didn't end out too well in his 2nd term.
What do you think? Can a presidential hopeful have a legitimate second try and win?