Colin Powell endorsed Barack Obama today on NBC’s Meet the Press.  The endorsement had been rumored for months, as Powell has made no secret of his disaffection from the Republicans since his retirement as Secretary of State. It gives Barack Obama much needed support on questions of foreign policy and military affairs in a period of time when people may question whether to trust a man with no experience at either.  But did Powell miss the window?

After months of hints and speculation, former Secretary of State Colin Powell endorsed the presidential candidacy of Barack Obama this morning, a huge vote of confidence in the Illinois Democrat with just 16 days left before the November election.

“He has both style and substance,” Powell said of Obama on NBC’s “Meet the Press”. “I think he is a transformational figure.”

As we wrote on Friday, the Powell endorsement carries huge symbolic importance — not only is he a former high-ranking member of President Bush’s Cabinet but he also was the most visible face in making the case for the war against Iraq.

Powell’s endorsement complicates any attempt by John McCain and others within the Republican Party to cast Obama as naive on world affairs and unready to lead in a dangerous time. Obama now has a ready retort: “Well, Colin Powell seems to trust my judgment; that’s why he endorsed me.”

I’m not going to impugn Powell’s motives here. He served his country honorably in every task assigned to him, and he’s earned the right to participate in the political process. Unlike endorsers like Christopher Buckley, Douglas Kmiec, or Michael Smerconish, Powell has never publicly identified himself as a conservative activist. He’s mostly stayed within the military and foreign-policy realm and could easily have served as Secretary of State in a Clinton administration as much as in a Bush administration. This doesn’t represent any hypocritical apostasy, and it doesn’t come as much of a surprise, either.

However, I don’t think this will have the same impact it may have had in the summer, for two reasons. First, I think most people expected Powell to endorse Obama, and most of us expected it at the Democratic convention. Powell hasn’t hidden his disdain for his former colleagues well, especially while his closest aide Richard Armitage spent most of his time ripping them. Coming as it does now, it may impact some voters who still feel uncomfortable with Obama’s lack of experience. Otherwise, I don’t think anyone likely to be swayed by this endorsement didn’t already factor it into their thinking.

In August, Obama could have used this when he fumbled the Russo-Georgian conflict. Now, though, foreign policy has dropped to the second tier for most voters. They’re more interested in economic issues, and I think Joe the Plumber has more resonance than Colin Powell at this point in the election. Powell, who has no experience in economic issues and has never spoken out on them, simply doesn’t figure into those concerns.

Powell’s endorsement still gives Obama a boost and certainly some gravitas. Does it really change the ground in this election? I’m skeptical. McCain needs to hammer on these economic themes to make Powell’s endorsement less relevant over the last two weeks.