Mitt Romney is learning what candidates before him learned. Small mistakes count, but usually not for much. But big ones can put a man down for the count. Right now, his "$10,000 bet" seems insignificant. His pleasure taken in "firing" greedy incompetents, taken out of context and exaggerated by opponents who know better, is slightly more damaging, but the fair-minded (as most Americans are) understand what he meant.
It's unlikely that a trip of the tongue will trip up the leader of the pack. Romney's rhetoric has been reliably steady, and the remark did not hurt him in New Hampshire. If it doesn't cripple him in South Carolina, he could wrap up the nomination in Florida 10 days later. If he doesn't have what George Bush the elder called "the Big Mo," he's got "the ongoing Mo."
Romney has carefully cultivated the perception that he would be a steady and expansive leader with a consistent vision for America. While the emphasis at this stage has been mainly on domestic policy, the Romney ace is the perception that he would restore dignity and depth to American leadership in the world.
The particulars of foreign policy are rarely a dominant theme of a presidential campaign except in time of war, and "foreign policy" didn't seem to count for much in Iowa or New Hampshire, but issues of "war and peace" will be nagging at the minds of many voters after they're satisfied the man they like can fix the economy. President Obama has so far had no steady hand in his foreign policy.
Ron Paul, the naive isolationist, isolates himself with his fanciful notions about the dangerous world about him, offering only a strategy of hoping for the best and counting on something good to turn up. The young love him because they have neither the knowledge nor sense of history. They don't like war (who does?), but Paul underestimates the enemy, especially in Iran. He dismisses as unimportant the foolish risk of dealing from a position of weakness.
Barack Obama was similarly naive in 2008, saying how willing he would be to sit down and talk with the leaders of Iran. Secretary of Defense Leon Panetta now insists Iran is not developing a nuclear weapon, despite the conclusion of the International Atomic Energy Agency that "Iran has carried out activities relevant to the development of a nuclear explosive device."