Talking heads on the tube may praise the aggressive, impassioned performance by Newt Gingrich in the latest GOP debate in Myrtle Beach, S.C., but it’s far from certain that his rhetorical skill will translate into votes on primary day this Saturday.

Clearly, the audience gave Newt the most rousing applause of the night and he may have rallied the flagging spirits of his nearly exhausted true believers. Any time Gingrich can take attention away from his unspeakably sleazy super-PAC ads (like the laughably heavy-handed “documentary” horror movie about Bain-and-pain, When Mitt Romney Came to Town) and focus attention instead on his own persuasive arguments, he undoubtedly helps his own cause.

But in the midst of all the hearty self-congratulation over at Camp Gingrich, it’s worth recalling that it wasn’t so long ago that media analysts heaped lavish praise on Michele Bachmann and Herman Cain for their sterling debate performances. With the Herminator, charges of inappropriate behavior ultimately upstaged his skill as a media communicator, but in Bachmann’s case, it’s arguable that her own confrontational tone in a climactic Iowa debate (in which conventional wisdom claimed she seriously dented Gingrich) actually helped do her in.

In considering the experience of this long and fascinating season of televised encounters, it’s worth recalling that the least aggressive, least angry, most even-tempered, and unflappable of all the candidates (Mitt Romney) has established himself as the prohibitive favorite to win the nomination.

This may reflect his focused and tightly controlled temperament, but it more likely stems from a conscious campaign strategy. The Romney and his team are winning the contest (and probably won the showdown in Myrtle Beach) because it demonstrates the best understanding of one of the most important rules of American politics: most people vote against the candidate who scares them most rather than voting for the contender who inspires them most. When choosing a president, the electorate prefers reassurance to excitement.

This tendency helps to explain the huge advantage enjoyed by most incumbents: if a sitting president looks even vaguely competent and reliable, threatening few unpleasant surprises or boat-rocking agendas, he most always wins reelection. When there’s no White House occupant on the ballot (as in 2000 or 2008) the public will generally choose the candidate who acts most like an incumbent—George W. Bush in 2000 and Barack Obama in 2008. By contrast to their measured, cool-customer demeanor, their opponents looked erratic and unpredictable: Al Gore seemed weird, unstable, gaffe-prone, and condescending; while John McCain was hyper-caffeinated, jumpy, and increasingly desperate in coming to terms with the financial meltdown.

Mitt Romney is running like an incumbent candidate, and it seems to work for him. By a wide margin, he came across as the least scary, least risky, most cautious choice on the stage at Myrtle Beach.

This may not produce huge enthusiasm in the Twitterverse (Fox News is already reporting that Ron’s Paulestinians gave him, as always, the most energetic response in social media), but it’s given Romney a huge lead in national opinion polls.

Remember the days when pundits nattered endlessly about Mitt’s inability to crack the ceiling of 25 percent support? In a Fox News national poll released on Jan. 14, Romney hit 40 percent—while Santorum, Gingrich, and Paul held between 13 and 15 percent each. Nothing that occurred in the Myrtle Beach debate should derail the steady momentum of Mitt’s machine.

Gingrich supporters may exult in their champion’s effective performance on the big stage and relish the dream that their guy could clobber Barack Obama in televised debates. It’s uncertain, however, how well the Newtster’s explosive personality (Peggy Noonan described him as “a human hand grenade”) would come across in contrast to the president’s well-advertised cool and self-control; no one should count on Newtonian fire trumping Obamian ice. It’s entirely possible that the bulky, scowling, heavy-browed Gingrich could seem like a truculent bully in contrast to that nice, polite and slim young  president (with his picture-perfect wife and daughters).

Most significantly, Republicans seem to be reaching toward a reasonable conclusion as the party coalesces around a plausible (if unexciting) nominee: it’s a good thing to win debates, but it’s a much better thing to win elections.