The debate on homeland security in the 2008 presidential election will be that of prevention versus response.

Last week, law enforcement officials in New Jersey broke up an Albanian-Islamic plot to attack American soldiers at Fort Dix. The special agent in Charge of Immigration and Customs Enforcement, John Kelleghan, praised the law enforcement action as a model of how post-9/11 police work is supposed to work.

A clerk, dubbing a video onto a DVD, noticed the alarming image of people dressed in military garb, firing weapons, and shouting threatening slogans. The investigation commenced when the clerk notified the local police, which, in turn, informed the FBI.

Republicans are comfortable with encouraging citizens to come forward and report suspicious activity. Mitt Romney, for example, appeared in New Hampshire last month trumpeting cooperation between members of the public and local and national law enforcement authorities. Following a meeting with the Rockingham County Chiefs of Police, Mr. Romney stressed the need to build up and expand joint intelligence gathering efforts on the part of government officials. He also said he opposed efforts to sue so-called John Does who report suspicious activity to authorities if those reports are unfounded.

For Democrats, it is easier to focus on first response. In recent days, Senator Obama has been met with criticism for his answer during the first Democratic debate on how he would respond to the destruction of two American cities by terrorists. “Well, the first thing we’d have to do is make sure that we’ve got an effective emergency response, something that this administration failed to do when we had a hurricane in New Orleans,” Mr. Obama responded.

Mr. Obama’s response has been interpreted as a mistake, flub, or sign of inexperience in presidential politics. Another answer might be that Mr. Obama could have been answering in accordance with his instincts, ones that are in-line with the need to attract Democratic primary voters. The answer Mr. Obama is trained to give to questions about disasters and terror attacks is likely one about how America should respond to the disaster. If that is the case, his answer, while probably too candid for an election forum, was not an unconscious flub but a flaw in his internal logic.

Six Democratic candidates marked the week of the foiling of the Fort Dix terror attack by paying homage to another aspect of homeland security — response to terror attacks. Senators Clinton, Edwards, Biden, Dodd, and Governor Richardson trekked to New Hampshire to speak to the International Association of Fire Fighters Convention, a powerful political group. Senator Obama addressed the gathering by phone.

Fire fighters still symbolize the best of heroism and the pinnacle of sacrifice on September 11. Their union has the ability to drape any Democratic candidate with a thick coat and helm to fend off criticism of being weak on terror.

Mrs. Clinton praised the heroism of the fire fighters she encountered as New York’s senator after the September 11 attacks, invoked legislation lobbied for by the IAFF, and reminded them of her support for the 9/11 health care bill. “We’re going to put together a package to take care of the people that are suffering from not just asthma and bronchitis … but of serious diseases of the lungs, where they can’t breathe any more.”

Mr. Biden talked about his plan to provide grants to local fire departments, the Biden COP program, interoperability, the ability of first responders working with different communication systems to speak to each other during an emergency, and the value of fire fighters in general. “We made a lot of promises to fire fighters after 9/11. And we haven’t kept a whole lot of them,” he said. “We don’t get you more fire fighters … then, guess what? We’re in real trouble when another Katrina or another 9/11 occurs.” Left unmentioned in transcripts and news accounts of the event was any discussion of preventing terror attacks.

Both the break-up of the New Jersey terror attack and the visit of the Democrats to the fire fighter association demonstrate competing visions of homeland security. Since September 11, neither Democratic politicians nor law enforcement officials would be so unwise as to express criticism of the legalities of the successful prevention of an act of terror. Nevertheless, there is an obvious considerable distaste for the help needed to crack a terror case before it happens.

It’s easy to imagine, say, a President Obama, placing more emphasis on the privacy rights of those like the customers at video stores than the imperative for citizens to report suspicious activity to authorities.

And, just below the level of the elected official, there is a layer of Democratic-leaning policy experts for whom the whole preventative aspect of homeland security borders upon civil rights violating alarmism.

Given the choice between alienating primary voters by pushing too hard on efforts to prevent terror attacks and winning the support of the fire fighters union that helped Senator Kerry win the Democratic Primary in 2004, it’s a lot easier to call for more first response dollars. The problem is that American voters need both.

Mr. Gitell (gitell.com) is a contributing editor of The New York Sun.