CAMBRIDGE – While the presidential primary elections in the United States are not over, Mitt Romney is now almost certain to be the party’s nominee to face Democratic President Barack Obama in November.As Governor of Massachusetts, Romney built a record as a competent and moderate conservative, a political profile that suited him to the state’s electorate. But the Republican Party’s far right wing dominates the primaries, so Romney has worked hard to escape the "moderate” label by staking out very conservative positions. Now, as the party’s presumptive nominee, he must move back toward the political center, where the majority of voters are to be found.So which is the real Mitt Romney? And how can voters judge the two candidates? Obama has a proven track record, albeit one that has disappointed many who voted for him in 2008. Of course, his supporters argue that he had to adapt to two ongoing wars and the worst recession since the 1930’s. Moreover, after the 2010 mid-term elections, a hostile Republican-controlled House of Representatives blocked his initiatives.Romney, for his part, will hold up Obama’s early, still-unmet promises, while Obama will call Romney a "flip-flopper” who changes his positions to suit the moment (and the audience). In fact, the difficulty of predicting the eventual winner’s performance in office is not new.In his 2000 presidential bid, George W. Bush famously promised "compassionate conservatism” and a humble foreign policy, but governed very differently, as when he decided to invade Iraq. Likewise, Woodrow Wilson and Lyndon Johnson campaigned on promises of peace, but each took America to war shortly after being elected.Do such post-election changes in direction make a mockery of democracy? How can voters make intelligent judgments when campaigns are so carefully scripted and slickly promoted?Leadership theorists suggest that we should pay less attention to leaders’ policy promises than to their emotional intelligence – their self-mastery and ability to reach out to others. Contrary to the view that emotions interfere with clear thinking, the ability to understand and regulate emotions can result in more effective thinking.As Supreme Court Justice Oliver Wendell Holmes reputedly quipped after meeting Franklin D. Roosevelt: "Second-class intellect, but first-class temperament.” Most historians would agree that Roosevelt’s success as a leader rested more on his good nature than on his analytical skills. The energy and optimism that he unleashed in his administration’s first hundred days did not reflect concrete policy proposals in his campaign.Psychologists have wrestled with the concept of intelligence, and how to assess it, for more than a century. General IQ tests measure dimensions of intelligence such as verbal and spatial dexterity, but IQ scores generally predict only about 10-20% of success in life. And, while experts disagree about how much of the other 80% is attributable to emotional intelligence, they generally agree that it is an important and learnable skill that increases with age and experience, and that individuals possess it to varying degrees.Leaders work hard to manage their public images, which requires some of the same emotional discipline and skill that successful actors possess. Ronald Reagan’s experience in Hollywood served him well in this regard, and Roosevelt was a master at image management. Despite his pain and difficulty in moving on legs crippled by polio, he maintained a cheery exterior and avoided being photographed in a wheelchair.Whether they realize it or not, leaders always convey signals. Emotional intelligence involves the awareness and control of such signals, and the self-discipline that prevents personal psychological needs from distorting policy. If emotional intelligence is inauthentic, others will likely find out in the long run.Richard Nixon, for example, was strong on cognitive skills, but weak on emotional intelligence. He was able to strategize effectively on foreign policy, but was less able to control the personal insecurities that eventually led to his downfall – a shortcoming that emerged only over time. Indeed, it was not until well into his presidency that the public learned of his infamous "enemies list.”Bush showed emotional intelligence in midlife by mastering his problems with alcohol, and in displaying the courage to persevere with unpopular policies. But, at some point, perseverance becomes emotional stubbornness. Like Wilson, Bush had an obstinate commitment to his vision that inhibited learning and adjustment. Perhaps the flexibility that Obama and Romney have shown is not such a bad quality for a president after all.The rigors of the prolonged campaign provide voters with some clues about stamina and self-discipline. Each of the Republican candidates took a turn as front-runner in this race, and the rigors of the primary season exposed the flaws in some, like Texas Governor Rick Perry, who were initially attractive. Now, in the general election, how Romney, in particular, relates to his party’s platform will tell us something about the strength of his independence and future cabinet appointments.But the most important variable for voters to examine is the candidate’s biography. I do not mean the slick books and television advertisements that are produced for their campaigns. While image consultants and acting ability can mask a candidate’s character, an integrated life over time is the best basis to judge the authenticity of the next president’s temperament and how he will govern.Joseph S. Nye, a former US assistant secretary of defense and chairman of the US National Intelligence Council, is a professor at Harvard University and one of the world’s foremost scholars of international relations.