Since the onset of the Cold War, national-security issues have not been kind to Democrats. Of course, the United States won World War II under the powerful leadership of Democrat Franklin Roosevelt. But since then, Democrats have mostly suffered when defense has ranked high on the agenda.

From 1900 to 1948, Democrats split presidential elections better than evenly, winning seven to the Republicans’ six. But from the beginning of the Cold War to the fall of the Berlin Wall, Republicans won seven presidential contests while Democrats managed victory in only three.

Two of the three Democrats who won in that period ran as strong on defense. Jimmy Carter, of course, was elected in the traumatic aftermath of Watergate. But John F. Kennedy, himself a war hero, ran against Nixon from the right on defense, arguing that the Republicans had allowed the growth of a dangerous “missile gap” to the advantage of the Soviets. (Upon assuming office, the president was chagrined to discover that this gap was wholly a figment of campaign imagination.) No one would accuse his successor, Lyndon Johnson, of being a dove.

The end of the Cold War helped give us two terms of Bill Clinton. But Sept. 11 put national security back on the table as a salient issue.

It was debilitating for Democrats in both 2000 and 2004. A Gallup poll just after the 2000 election found voters saying Republicans were “tough enough” to deal with terrorism by 64 to 27 percent. However, just 34 percent thought Democrats were tough enough to meet the threat, compared to 57 percent who said we were not.

The 2004 election year proved little different. The exit polls found voters trusting Bush to deal with terrorism by an 18-point margin and mistrusting Kerry on the issue by the same 18 points. While much was made of the 22 percent who said they cast their ballots on “moral values,” 19 percent said terrorism was their primary issue, and those voters supported Bush by a 72-point margin, the largest advantage for either candidate on any issue.

Bush’s failure in Iraq has altered the dynamic on national security in important ways. But doubt about the Republicans is not the same as confidence in Democrats. As long as terrorism is on the national agenda, it will be difficult for Democrats to win unless voters trust us to protect the nation.

At least two important initiatives are under way to help rectify the problems confronting Democrats on national security.

A group of House experts, led by Minority Whip Steny Hoyer (D-Md.), has released a vision for “Ensuring America’s Strength and Security,” identifying defending the homeland, defeating terrorism and promoting democracy and human rights as central policy objectives.

Their specific solutions range from improved intelligence directed specifically at the terrorist threat to making the United States independent of Middle East oil to working with the Russians and others to secure loose nukes. It is a wise compendium that recognizes that we must be smart as well as strong, that we must be willing to use force but always stand for our core values, that we must be willing to act alone when necessary but we are stronger when we act in concert with allies.

One member of Hoyer’s group, Rep. Jane Harman (Calif.), the ranking Democrat on the Intelligence Committee and a widely recognized expert on national-security issues, is also taking a bold step by organizing SecureUS, a political action committee that will bring together good substance and effective politics to develop messages that can help Democrats overcome the national-security hurdle. Having tapped the expertise and developed the language, Harman’s SecureUS will train Democratic candidates in becoming effective advocates for strong and sensible security policies.

Building trust on national security issues will be difficult for Democrats, but it is vital.

Mellman is president of The Mellman Group and has worked for Democratic candidates and causes since 1982, including Sen. John Kerry (D-Mass.) last year.