As this is written, with a deadline looming, I have not heard Barack Obama's acceptance speech at Invesco Field and have not learned who is John McCain's choice for vice president.

You know more about these things than I do. So I will write about something I may know more about, and which has been the subject of some concern at the Democratic National Convention: the Democrats' charge that Republicans make illegitimate attacks on their candidates, attacks that imply that they are far out of the American mainstream. The two examples they cite are the "Willie Horton" ads against Michael Dukakis in 1988 and the Swift Boat Veterans for Truth ads against John Kerry in 2004.

But both attacks were well within the bounds of fair political comment. Dukakis supported for 11 years a policy of granting weekend furloughs for prisoners sentenced to life without parole. Willie Horton, one of those furloughed, fled and committed another violent crime.

There's a reasonable argument for granting weekend furloughs to prisoners scheduled to be released in six months or so. Voters may not agree, but few will consider the policy outrageous. But there is no rational argument for letting loose a prisoner who is supposed to stay behind bars the rest of his life. Democrats now criticize Dukakis for not fighting back. But what argument could he have made?

As for Kerry, I listened respectfully to the majority of his boatmates who said that he acted heroically and to the majority of the larger squadron who said that he did not. They were talking about events that happened long ago, in sudden violence, and I found myself unable to say those on either side were lying.

But I also saw Kerry's campaign abandon his claim -- that he said on the Senate floor in 1986 was "seared, seared" in his memory -- that he was in Cambodia at Christmastime 1968. And I never heard him repudiate his 1971 Senate Foreign Relations testimony -- featured in the ads -- that our soldiers committed "crimes ... on a day-to-day basis with the full awareness of officers at all levels of command."

I used to be a Democratic campaign consultant. In that capacity, I would have advised the Dukakis campaign to admit early on that the furlough policy was a mistake. I would have advised the Kerry campaign to go before a veterans' group early on and apologize for the Foreign Relations testimony. Voters understand that candidates sometimes make mistakes and that young men say outrageous things that in time they come to regret.

Which brings us to Barack Obama. He has three major vulnerabilities here as I see it. One is his 20-year relationship with the Rev. Jeremiah Wright. Polls suggest he has sustained some damage on this, and it's not clear whether video clips of Wright saying "God damn America" will inflict more in the fall despite the candidate's repudiation of those comments.

Another problem is Obama's relationship with the unrepentant Weather Underground terrorist bomber William Ayers. In an April debate, Obama portrayed Ayers as a casual acquaintance. But Ayers was co-founder of the $49 million Chicago Annenberg Challenge education program and Obama its chairman of the board. The Obama campaign has sued to take off the air ads highlighting the Ayers relationship and tried to intimidate a radio station for hosting a conservative who is examining the Annenberg documents in the Richard J. Daley Library.

Finally, there is Obama's 2003 vote against a bill, "virtually identical" as the Obama campaign admits, to one that passed the U.S. Senate 98-0, banning the killing of fetuses who have survived abortions.

Liberals like Obama tend to go over the line between positions and associations that most voters find reasonable (though they may not agree) and those they find outrageous. They assume, usually correctly, that mainstream media will be reluctant to report on the latter, as has been the case in all those mentioned above. Conservatives take more care to separate themselves from the outrageous because they know mainstream media will pounce on them if they don't.

On Ayers, the Obama campaign has tried to suppress discussion. But it will likely fail. The emergence of new media and the First Amendment mean that is like stopping the Mississippi River from flowing to the sea. If I were advising Obama, I would tell him to confess error, as he arguably has on Wright, on both Ayers and the Born Alive Protection Act, lest they cause his campaign as much damage as the furlough ads caused Michael Dukakis and the Swift Boat ads caused John Kerry.