WASHINGTON -- John McCain has been relentlessly pounding Barack Obama on his weakest ground: experience, fighting the war on terrorism and his judgment in world affairs.

And with good reason: Recent voter surveys show Obama's polls on these critical presidential-leadership qualities are in the basement and that Americans trust McCain far more on all three issues than the youthful and inexperienced freshman senator from Illinois.

His scores aren't just so-so mediocre -- they are failing grades that pose disturbing questions about the Democratic presidential front-runner's tissue-paper-thin qualifications to be commander in chief and the leader of the free world.

Consider these abysmal grades from a recent ABC/Washington Post survey that asked voters to compare Obama with the veteran Arizona senator:

-- Regardless of who you may support, who do you think (Obama or McCain) has the better experience to be president?

McCain: 71 percent, Obama: 18 percent.

-- Regardless of who you may support, who do you think has better knowledge of world affairs?

McCain: 65 percent, Obama: 24 percent.

-- Regardless of who you may support, who do you trust more to handle the U.S. campaign against terrorism?

McCain: 55 percent, Obama: 34 percent.

Little wonder, then, that McCain has chosen to attack the senator on the same grounds, using even the same words, as Hillary Clinton did earlier this year when Obama said in a Democratic debate that he would sit down and negotiate with the world's most dangerous leaders of rogue nations without any preconditions.

People like Iranian President Mahmoud Ahmadinejad, who has said he wants to wipe Israel off the face of the earth, who believes that much -- if not most -- of the Holocaust is a fiction invented by Jews, who has been arming terrorists in Iraq to kill American and Iraqi soldiers.

Earlier this year, Clinton called Barack Obama's positions "naive" and dangerous and said it showed he did not have the experience to be commander in chief with the responsibility for protecting America's national-security interests and those of our allies.

McCain reopened that issue last week, saying Obama was "naive" and demonstrated "reckless judgment" when he said he would meet one-on-one with Ahmadinejad -- giving the Iranian strongman the prestige of a presidential summit without extracting any concessions. Continued...