Now that we have seen both parties’ national conventions, it is clear that the 2004 presidential contest is likely to come down to a rather simple question: What is this election about?

Is it terrorism and President Bush’s handling of the war on terror? Or is it the war in Iraq, Sen. John Kerry’s (D-Mass.) service in Vietnam and the economy?[IMGCAP(1)]

Historically, the two parties fight each election over a handful of issues (usually concerns such as unemployment, education, the federal deficit, education, taxes or health care) that both parties acknowledge will determine the winner of the White House. Each presidential nominee stakes out his ideological ground and argues that his agenda is better for the country than his opponent’s.

This year, however, it isn’t so easy to identify the top issue. Polls show that roughly equal numbers of Americans identify jobs and Iraq/terrorism as the most important issue facing the country, and Americans are split over whether the war on terrorism and the war in Iraq are parts of the same conflict or two separate fights.

While Kerry says he would have voted to authorize the attack on Iraq even if he knew then what he knows now, most Democrats believe that the war is unnecessary and that Saddam Hussein had nothing to do with the attacks of Sept. 11, 2001.

Republicans don’t agree at all. When Sen. John McCain (R-Ariz.) told delegates on Monday night that “our mission [in ousting Saddam Hussein from power] was necessary, achievable and noble,” he was making an unapologetic argument about the war, defining it as part of the larger struggle against terrorism that began the moment terrorists attacked New York’s World Trade Center.

The latest ABC News/Washington Post poll, like other surveys, shows the horse race as a dead heat, not in itself bad news for the Democrats. But when asked whether they trust Bush or Kerry more on a series of important issues, Americans give Bush better marks on the important issues of the day.

While the challenger holds an advantage on health care (50 percent to 43 percent) and prescription drugs (51 percent to 38 percent), the president is seen as doing a better job handling both Iraq (52 percent to 44 percent) and terrorism (56 percent to 38 percent).

If voters decide that they are casting their votes on the state of the U.S. economy or the conduct of the war in Iraq, Kerry has a good chance to win in November. The public’s apparent desire for change (as reflected in right direction/wrong track polling) favors the challenger.

But if the 2004 contest is a vote about which candidate Americans want to conduct the war on terror for the next four years, Bush will be returned for a second term.

It’s probably as simple as that.

With the Republicans devoting the better part of four days to trying to convince the American public that Bush has been a strong leader on the war against terror (and that Kerry would be much more risky as a leader), it is likely that the president’s advantage on the issue will grow.

Kerry has contributed to the overall focus of the campaign on military matters (as distinct from the economy) by running on his Vietnam résumé. He certainly needed to establish his — and his party’s — credentials on defense and national security. But the Kerry campaign was overly optimistic about its ability to erase the GOP’s advantage on defense and national security, and it has failed to keep public attention on those issues on which the Democrats have the edge.

Kerry’s campaign has finally acknowledged the error of its ways and has released a couple of new ads that use economic appeals. In addition, the Senator came out swinging in an Ohio stop minutes after the Republican convention ended late Thursday night, defending himself against the GOP attacks on his defense and foreign policy record.

Kerry must continue to refocus attention on issues that favor him over Bush while at the same time continuing to stress his credentials as a prospective commander in chief.

The basic dynamics of the 2004 race remain unchanged from two months ago. Voters don’t seem entirely happy with the president. But they aren’t thrilled with Kerry.

The Massachusetts Democrat’s new confrontational style may give him the initiative in the race — or reinforce Bush’s reputation as the likable candidate. But Kerry had to do something to change the day-to-day developments, most of which were breaking the president’s way.

If Kerry starts dictating the race’s agenda, he can put Bush back on the defensive and score points on issues of his choosing. If he fails to do so, Democrats will form a circular firing squad and begin shooting at each other. If that happens, it will mark the beginning of the end of the Kerry campaign.

Stuart Rothenberg is editor of the Rothenberg Political Report.