Senators Barack Obama and John McCain will have three opportunities to debate their substantive policy differences before Election Day in November. With both candidates proposing significant changes in tax and health policy, the debates will be an important opportunity for policy-minded voters to hear their proposals. Although Obama emphasized economic issues at the Democratic convention, he may have a difficult time defending his high-tax and protectionist-trade policies against his rival.

Senior Fellow  Kevin A. Hassett

Now that the conventions are behind us, most Americans will now turn their attention back to the school year and the National Football League. There will be few moments when the campaigns can, as they did over the past two weeks, grab everyone's attention.

That leaves the candidates with only one more high-visibility opportunity to reach undecided voters: the debates.

There will be three debates between Senators John McCain and Barack Obama in late-September and mid-October, with one vice-presidential meeting of Senator Joseph Biden and Governor Sarah Palin between the second and third presidential debates.

One of the presidential debates will focus on foreign policy, another on domestic policy, and a third will feature a town-hall format where the public poses questions to each candidate. The vice presidential contenders will cover both foreign and domestic topics.

Make no mistake, these debates will be enormously important.

They have often been viewed as decisive in races that are, like this one, tight. Both John F. Kennedy and Ronald Reagan probably became president because their powerful magnetism overwhelmed less-charismatic opponents. Gerald Ford might well have lost his election to Jimmy Carter because of his colossal debate blunder, incorrectly saying the Soviet Union didn't dominate Eastern Europe. He became a laughing stock at just the wrong time.

Economics Lessons

This time, the debates may turn on subtle issues of character or unpredictable blunders, but voters will also be looking closely at substance, especially on economic policy.

The good news is, if history is any guide, voters can expect to learn a lot about economic policy in the coming weeks. Economic policy has been front and center in presidential debates ever since the first televised Kennedy-Richard Nixon one in 1960. Surprisingly, at least for critics, the economic conversation has often been quite substantive.

Looking back over the debates that occurred from 1996 to 2004, a number of interesting patterns emerged. First, there are two big subjects that receive the lion's share of the attention.

Out of 57 economic-related questions in presidential debates over that time, 18 addressed health care and 16 were about tax and the budget. Much of this year's debates will probably be devoted to those two issues. As McCain and Obama have extensive health-and-tax plans, there will be plenty to talk about.

Dodging Questions

The next two most frequently addressed topics are Social Security and trade. After that, all bets are off, with questions ranging from the state of the Cleveland economy to the impact of trial lawyers on the U.S. economy.

How will the candidates do? Looking at past debates, they often seemed to turn on questions that the candidates were able to dodge until the debate.

Four years ago, Democrat John Kerry whiffed when moderator Charles Gibson asked him to explain how he could cut the deficit in half while increasing taxes only on the rich. Al Gore couldn't defend himself against the accusation that he proposed to boost spending more than Michael Dukakis and Walter Mondale combined.

On substance, it seems likely the Democrats will face the tougher and more treacherous questions, especially with regard to the two big topics--health care and the federal budget.

On health care, the Obama plan calls for a large tax increase on businesses that have to "pay or play'' with regard to health insurance. On taxes, the key distinction between Obama and McCain is Obama's desire to increase taxes on those with incomes of more than $250,000, and his opposition to McCain's proposal to reduce taxes on U.S. corporations.

Tax Increases

Both the health plan and the tax plan revolve around increasing taxes. But the economy is struggling. Nobody thinks it's a good idea to raise taxes during a recession. Obama and Biden will have a difficult and swaying tightrope to walk.

The other tricky area for Obama will be trade. He has staked out a position that is hostile to free trade. Yet second-quarter gross domestic product grew 3.3 percent, with 3.1 percent of that coming from net exports. Exactly how is it that one can make the case that our trade deals are hurting the country?

The trade area is ripe territory for tough questions. After all, we now have trade deals with Panama, Colombia and South Korea that are ready for passage but are being held up by Democrats for purely political reasons. U.S. companies are paying millions of dollars in tariffs every day to the Colombian Treasury because of congressional obstructionism on trade. Isn't it more important to lighten the load on U.S. businesses now that the economy is weak?

For McCain, the tax cuts will be easy to defend, especially now when the economy is weak. The challenge will be to make the case that he will be able to constrain government spending enough to make his fiscal program sustainable. Talking tough on spending comes naturally for the man, however, and one can expect that he will be up to this challenge.

It seems likely that the story of these debates will turn on the dissonance lurking below the surface in Obama's economic plans, and on his team's ability, or lack thereof, to address it.

Kevin A. Hassett is a senior fellow and director of economic policy studies at AEI.