David From explains that Americans are still concerned about a president’s ability to protect the United States in a dangerous world, and that the public has not failed to recognize the democtrats’ record of insincerity and opportunism.

Democratic populism is destroying Democratic credibility on national security.

Let’s go to the numbers.

Republicans have owned the national security issue since the late 1960s. After 9/11, the Republican advantage on poll questions spread to an astounding 30 points.

But since 2005, the Republican advantage has dwindled. By the fall of 2007, the two parties had reached near parity on the issue, only 3 points apart—the best Democratic result since Barry Goldwater led the Republican party!

That parity did not last. Over the past year, Republican standing on the issue has revived while Democratic credibility has tumbled. In Greenberg’s latest polling, the Republicans now hold a 14-point lead, 49-35, a return to the kind of advantage they held in the 1980s.

What’s going on?

Greenberg advances three reasons, but here is the most important and provocative:

When asked to choose why they think Democrats are weak on security, the number one reason—picked by 33% of all respondents—is that Democrats” change positions depending on public opinion.”

“Moreover, when we ask respondents to compare the two parties, likely voters choose Democrats over Republicans as the party “too focused on public opinion” by a 27-point margin. Even Democratic base voters agree: liberal Democrats point to their own party as the one “too focused on public opinion” by an 18-point margin, and moderate/ conservative Democrats say this by 25 points.

In 2001-2002, Democrats chased public opinion in a hawkish direction. In 2004-2007, they chased public opinion in a dovish direction. In 2006, when the war seemed hopeless, that reversal paid off for Democrats. But as conditions have improved in Iraq, Republicans have been vindicated—and Democrats look weak and opportunistic.

Now when Bob Shrum talks of “populism,” he has something very specific and highly ideological in mind. But most Americans—and most working politicians—use the word “populism” in a more general sense. They use it to mean, “doing what is popular.”

You might think that doing what is popular is always good politics. That would seem true almost by definition!

And in the very short term, it has been true for Democrats.

But there is a longer term too. Voters remember. They compare results. They recall who stayed firm in the moment of decision and who flinched. And if the person who stood firm is also proven right—voters reward it.

Don’t misunderstand. There are prizes for the vacillating and the time-serving. John Kerry is still senator from Massachusetts after all. But there is a price to be paid too for too obvious vote-catching—and on national security, the Democrats have already begun to pay it. Just how high that price will go, we must wait until November to know.