Richard Nixon lost the presidency in 1960, was pilloried in his own party for losing to so inexperienced an opponent as John F. Kennedy and eight years later was elected to the White House. Ronald Reagan tried twice, in 1968 and 1976, and didn't win the Republican nomination until 1980, when he was elected president.If you and I know that, then surely Mitt Romney does, too -- and there are growing signs Romney, fortified by the conviction he was right more often than he was wrong in his campaign against a president who now suffers from plunging public support, may be looking at a third presidential race as well.This is not merely musings for a September morning. Nationally regarded Republican political operatives -- among the party's shrewdest and most experienced analysts, mostly of the breed who recoil at the thought of Rand Paul of Kentucky or Ted Cruz of Texas heading the GOP ticket -- are talking privately of the appeal Romney might have in 2016.If the Republican insurgents look as though they will split the primary vote, and if former Gov.