Sen. Barack Obama is, finally, the presumptive presidential nominee of the Democratic Party -- no mean achievement in this most hotly contested primary race in recent history. He deserves a day or two to bask in this glory -- and certainly the media have been helping this along with fawning coverage of his "historic" achievement as the first African-American to win a major party nomination. But at some point, surely, the press will get back to doing their jobs; namely, asking tough questions of Sen. Obama so that the voting public will learn more about the man who could be their next president.

The media should start by focusing on Sen. Obama's proposals in the foreign policy arena. He has offered a pretty radical vision of what his campaign calls "direct presidential diplomacy," offering to sit down, without preconditions, with some of the world's worst tyrants. He first made the offer in the heat of a presidential debate in which he was trying to contrast his approach with the current occupant of the White House.

In July 2007, Obama was asked by a YouTube questioner, "… would you be willing to meet separately, without precondition, during the first year of your administration, in Washington or anywhere else, with the leaders of Iran, Syria, Venezuela, Cuba and North Korea, in order to bridge the gap that divides our countries?" His answer was simple and direct: "I would. And the reason is this, that the notion that somehow not talking to countries is punishment to them -- which has been the guiding diplomatic principle of this administration -- is ridiculous."

Since then, he's been hedging and qualifying his statement, most recently with respect to Iran when he addressed the pro-Israel group AIPAC on Wednesday. Obama tried to reassure the attendees -- who are understandably worried about a nuclear-armed Iran, as everyone in the world should be -- by saying he'd engage in "careful preparation" before any talks begin. But then he did what he often does. He pretended he hadn't said earlier what he clearly had: "I have no interest in sitting down with our adversaries just for the sake of talking," he claimed, blaming the confusion on his adversaries.

There are two issues here. One is foreign policy naivete. His original statement suggests he has no idea how diplomacy actually works. As a well-meaning amateur trying to rewrite the rules to conform to his idea of how the world should be, Sen. Obama could endanger the very security he seeks. But the other issue -- and the one the mainstream press has so far largely ignored -- is Sen. Obama's truthfulness.

It is one thing for Sen. Obama to say that he spoke too rashly in July and that he wants to amend his position. Political candidates make mistakes, sometimes saying things they don't quite mean. We all do. And the best way to put the episode behind him is to own up to it. But Sen. Obama can't seem to bring himself to do this because it would shine too bright a light on his inexperience in the foreign policy arena. So, instead, he says, in effect, he never said that.

The media are usually pretty eager to catch a politician in a contradiction. They are usually aggressive whenever a candidate changes his or her story, even when the matter itself is trivial. So why haven't the media been more dogged on Sen. Obama's misrepresentations of his willingness to sit down with dictators?

The point isn't for journalists to take a position on whether Sen. Obama's proposal to engage in direct talks with the likes of Raul Castro, Hugo Chavez, Kim Jong Il, or Mahmoud Ahmadinejad would be a good idea or a bad one. But they should be interested in why Sen. Obama said it was the right approach in July and has now backtracked, and in the case of Iran anyway, wants to pretend he never said it was.

Sen. Obama's sleight of hand raises an important issue of character. And the media have traditionally played an important role in helping voters define a candidate's character by asking tough and probing questions. So far, they've been reluctant to do so with Sen. Obama, certainly on substantive matters. It's time they start.