WASHINGTON — Colin Powell demonstrated his eponymous “Powell Doctrine” of overwhelming force on Sunday when he endorsed Barack Obama on “Meet the Press.” The one-time chairman of the Joint Chiefs of Staff systematically marshaled his assets to neutralize the Republican endgame strategy, which is to suffuse the air around Obama with a vague mist of terrorism, socialism and “otherness.”

Powell was so definitive that it was easy to forget the disconnect: Obama made his reputation with a speech in 2002 warning against war in Iraq, while it was Powell who went before the United Nations and used his credibility to build support for the Iraq invasion.

Powell told Tom Brokaw that he still believes that war was the right course of action, based on what he and other officials knew — or thought they knew — at the time. He said he believes the war was mishandled. And he said he still opposes a “deadline” for withdrawing U.S. troops, though he added that a “timeline” for withdrawal is beginning to emerge.

That would be a fair summation of John McCain’s position on Iraq, not Obama’s. Powell framed his endorsement largely in terms of how McCain, Sarah Palin and their supporters have conducted the campaign against Obama — and what that conduct says about McCain’s judgment. It was hard not to conclude that Powell is offended by some of the Republican tactics and that he has decided to fire back in a way that Obama cannot.

On the attempt by McCain and Palin to use Obama’s acquaintance with Vietnam-era radical William Ayers to suggest that Obama is somehow linked to terrorism:

“This Bill Ayers situation that’s been going on for weeks became something of a central point of the campaign. But Mr. McCain says that he’s a washed-out terrorist. Well, then, why do we keep talking about him? And why do we have these robo-calls going on around the country trying to suggest that because of this very, very limited relationship that Senator Obama has had with Mr. Ayers, somehow Mr. Obama is tainted? What they’re trying to connect him to is some kind of terrorist feelings.”

On the campaign of lies, spread by whisper and e-mail, to convince people that Obama is a Muslim:

“Well, the correct answer is, he is not a Muslim, he’s a Christian. He’s always been a Christian. But the really right answer is, what if he is? Is there something wrong with being a Muslim in this country? The answer’s no, that’s not America. Is there something wrong with some 7-year-old Muslim-American kid believing that he or she could be president? Yet I have heard senior members of my own party drop the suggestion, ‘He’s a Muslim and might be associated with terrorists.’ This is not the way we should be doing it in America.”

And on Palin’s qualifications and readiness to assume high office, an issue that a few conservative commentators have taken on but Democrats refuse to touch, as if it were radioactive:

“I was also concerned at the selection of Governor Palin. She’s a very distinguished woman, and she’s to be admired; but at the same time, now that we have had a chance to watch her for some seven weeks, I don’t believe she’s ready to be president of the United States, which is the job of the vice president. And so that raised some question in my mind as to the judgment that Senator McCain made.”

As the highest-profile Republican to defect to the enemy camp, Powell knew that his endorsement would create a huge stir. What I found fascinating was how he framed it more as a set of reasons to vote against the McCain-Palin ticket than a set of reasons to vote for Obama and Joe Biden. In talking about the Wall Street meltdown and the economic crisis, for example, Powell spoke of how McCain’s herky-jerky response made it seem that he “didn’t have a complete grasp” of what was going on. Powell went on to praise Obama’s “steadiness” — but mentioned nothing in particular that Obama actually did.

To those who would say he is only supporting Obama as a fellow African-American, Powell pointed out that if this were the criterion he could have made his endorsement months ago. Much more important, I think, is the fact that Powell is a moderate Republican who listens to all this innuendo about terrorism and all this rhetoric equating the income tax with socialism and wonders what in the world has happened to his once-grand old party.

The rhetoric he used to take his party to task followed the principle he made famous in the first Gulf War: overwhelming force.

Eugene Robinson is a Washington Post columnist. His e-mail address is eugenerobinson@washpost.com.