Bush has one thing in common with Truman: terrible poll numbers during his second term. Truman is well regarded today. That's the only reason Bush supporters even bring up Truman's name. Nixon would be a better comparison.

More than anything else, I think this highlights the foolishness of the WWHTD? approach to national security policy. Bush's foreign policy is a disaster. Whether or not it in some regards does or doesn't resemble things Truman did is neither here nor there.

Wrong, wrong, wrong.  The liberal hawk argument is not about the similarity between Truman and Bush, it's about the lessons learned from Truman in his approach to dealing with a totalitarian foe and specifically what those lessons hold for DEMOCRATS.  What are those lessons?

• Resoluteness: Truman came across as clear in his principles and didn't gnash his teeth making decisions.
• Faith in international institutions: Truman and Acheson built the entire infrastructure of postwar diplomacy, a structure that Republicans opposed at the time and have sought to undermine for most of the last 60 years.
• Judicious exercise of American power: Truman built international institutions partly because it would, to a certain degree, cosset American power, thereby building trust among the countries we needed to help fight the cold war.  More to the point, continuing American influence depended on NOT taking every opportunity to use force.

These principles are directly relevant to the argument today.  When staking out what a Democratic national security policy should look like, we could do a lot worse than keep these things in mind.

But the primary issue with Truman is that he sketched out a way to present a liberal national security policy in a way that worked in an American political context.  This is the lesson that left wingers never learn.  ONLY hawks win presidential elections.  ONLY candidates that are unashamed of American power and unafraid to use it stand a chance of building a national majority.  There are no exceptions to this rule.  If the Democratic party were to become captive to the kind of people who think any exercise of American power and influence is bad - and the influence of these people is growing - then we can expect to continue to lose, regardless of how incompetent the GOP is.

Truman was anything but mediocre.

This link will outline his legacy on foreign relations, domestic policy and partisan politics.

Nitpick altert!

I don't think that HST was "pushed" into using the atomic bomb by his military advisors.  Rather, since the inception of the Manhattan Project, the assumption was that the device (S-1) would be used.  There's an awful lot of evidence for this -- that it is false, in many ways, to speak of a "decision" to use the atomic bomb. 

There's also a fair amount of historical debate about the exact legacy of Hiroshima, something that was quite apparent in the upset over the proposed Smithsonian exhibit of the Enola Gay.  (Although that tended to pit historians against veterans' groups, but that's another story.)

well now, let's see: i guess when lbj ran that ad in '64 that suggested that goldwater couldn't be trusted with his finger on the nuclear button, that contributed to his devastating defeat.

and surely it was carter's all-encompassing hawkishness that won him the '76 election.

and everyone knows what a hawk bill clinton was in '92 and '96....

Your three points about Truman are generally accurate, and they speak to the reasons why he is well regarded as a historical figure.

But here are some other relevant facts:

There are many lessons the Democrats can learn from Truman. For starters, a tough, no-nonsense persona is an asset when you're trying to sell the American people on a policy of restraint and international cooperation. Perhaps more importantly, he had the guts to stand up to the wingnuts when they called him a coward for backing away from an unwise fight, and Americans respected that.

What he absolutely does not teach us, is that only "hawks" can win elections in America.

Americans, by and large, are NOT "hawks." They want leaders whom they can trust to protect us in a crisis. They will not vote for unilateral disarmament or politicians who appear weak and hesitant. Most voters do not find leftist rhetoric about the dark side of American hegemony to be appealing. But they also do NOT want their leaders to get our troops bogged down in foreign wars. Such wars inevitably become unpopular over time.

And liberals shoot themselves in the foot, time and again, by falling all over themselves to prove how resolute and hawkish they are.