Foreign policy has always been a challenge for challengers. They usually start with no record, and polling these issues can be particularly tricky because the public has a significant knowledge gap.

When we look at domestic issues like education, health and taxes, there's a strong likelihood that a voter has an education, goes to the doctor and works. Compare that to how many folks have been to Syria or Libya or have any sort of expertise on these topics, and you've got a message-testing conundrum. It's kind of like a corporate marketer asking someone who has never had soda whether he or she prefers Coke or Pepsi.

As a result, skillful pollsters can get the public to say really whatever they want. If we ask, "Should the President work to end the war in Afghanistan?" people will overwhelmingly say, "Yes!" But if we ask, "Should the President do what it takes to defeat the Taliban in Afghanistan?" people will also overwhelmingly say, "Yes!" Those two things don't go together in real life.

This muddled issue environment on foreign policy, national security and defense means that candidates need to up their game. Instead of being able to score points on issues by being pro-choice or supporting small business tax cuts, candidates need to clear different hurdles.

First, does the candidate connect with the emotions of the electorate? If people are scared, does he understand why? If people are angry, does he connect with that sense of anger? Second, does the candidate exhibit steady leadership? Is this a person you want handling nuclear launch codes? Sometimes we call this the “commander in chief test”. Third, do the key validators agree with the politician? What does the military think? How about our intelligence community? Do real experts agree with the candidate, or is he just trying to sound good for the dial test?

A combination of emotional connection, leadership persona and the validation of the security community builds public trust. Had Romney understood this better, he might have launched his Libya attack in a very different manner in the second debate. Instead, he failed on all three counts, and Obama had his best moment of the debate. (And conservatives are still out for Candy Crowley's head!)

By contrast, Obama enters tonight's debate with a high degree of trust on foreign policy and national security leadership. He did, after all, give the orders that took out Bin Laden, most of the other top terrorists in the world, Somali pirates and a dictator in Libya. So Romney's challenge will be to shake that faith, while Obama strives to maintain his credibility.

Right now, there are five major security issues that are registering strongly with the public, and I'll discuss the major goals of a successful Obama response for each.

1. Defense cuts. Shift the frame from Democrats wanting cuts, and explain that the far right is holding the defense budget hostage to get more tax cuts for millionaires. Use this new frame to lay out a simple case of priorities; both economic strength and military strength keep America safe. So the goal is matching spending to the threats we face, not pegging defense spending to GDP. Remind Romney that a strong defense budget doesn't end with war appropriations but includes how we take care of the troops afterward, and discuss the current administration's many successes with veterans and military families.

2. Iran. Recognize that Iran's nuclear ambition is the No. 1 perceived threat to America. Clearly explain that the current policy is economic warfare, the world has bought in and it’s working to isolate Iran. Internally, Iran is changing its mind about the value of pursuing nuclear ambitions. By contrast, bombing Iran is perceived very poorly by the military and intelligence community because it's only a 2 to 4-year-long solution, likely results in massive risks to our allies like Israel and could cause more terrorist attacks on US soil. For more on this, see the Iran war game we've launched.

3. China. Strike the right balance; China isn't our friend, but the middle class won't fair well if we start another Cold War with them—like some of Romney's old-school advisers want. Frame China as a serious competitor, who needs to follow the rules. Explain the many steps we've taken to level the playing field, and remind voters that Romney is financially tied to Chinese success—at the expense of American workers.

4. Energy. Energy has been largely left out of the debates, but it’s a huge national security concern. The energy frame is America controlling its own destiny, which comes through increased domestic production and competing with China and Europe to develop next-generation clean energy sources. Oil is a bad guy here; oil revenue funds our enemies, and oil dependence harms military operations because supply convoys are major targets. Remind Midwest swing voters how many jobs come from wind manufacturing, remind Southwest voters that solar can make them rich and remind America that GOP equals the Grand Oil Party.

5. Arab Spring. In the minds of voters, this includes Libya, Syria, Egypt, Yemen and just about any other country with a big Muslim population, the letter "y" in its name or some level of violent unrest. Commander in chief presence is the name of the game, since not even experts have any idea what to do in these places or what will happen—regardless of who is elected in two weeks. Body language matters! Avoid a quicksand of details, while transitioning to a broader, possibly even inspirational, vision of America's role as a world leader. Obama should dismiss Romney's critiques quickly and use this chance to remind people of why you inspired them in 2008.

Finally, Obama needs to expect a steady string of attacks and use a unifying thread to steadily discredit these attacks. A line like, "Governor Romney, as commander in chief you can't just criticize; you have to lay out and execute a plan," should be used over and over again, as a theme to challenge Romney's fitness for the role.

Michael Moschella is the national political director for the Truman National Security Project, which works to train candidates and political organizers at all levels.