WASHINGTON (CNN) -- The Democratic National Committee may be demanding an apology from Sen. John McCain about his comments Wednesday about U.S. troops, but one of his fellow presidential contenders on the Democratic side is defending the Arizona Republican.

"The one area I don't think he can be questioned is his dedication to American troops," said Sen. Barack Barack Obama, D-Illinois, who appears to be still smarting from his own gaffe last month about U.S. troops.

Appearing on "The Late Show With David Letterman," McCain said, "We've wasted a lot of our most precious treasure, which is American lives."

Asked Thursday whether McCain should apologize, Obama responded, "We have a duty, a sacred duty, to make sure we are honoring their sacrifice by giving them missions in which they can succeed. I'm positive that was the intent in which he meant it."

Obama added, "It was the same intent that I had when I made my statement, John McCain and I may have disagreements. The one area that I don't think he can be questioned is his dedication to American troops. He's been there. He's done that."

On his first official campaign trip in Iowa last month, Obama said "We now have spent $400 billion and have seen over 3,000 lives of the bravest young Americans wasted."

Obama, who is seeking the Democratic presidential nomination, apologized the next day, calling it "a slip of the tongue."