Following Hillary Clinton's get-over-it speech on Tuesday night at the Democratic convention, I was at a swanky party, and a political consultant I've known for years--a smart fellow who has been essential to the careers of several prominent Democratic legislators--walked up to me and said that the Barack Obama campaign had made a serious strategic mistake. "We've had two soft nights," he complained.

The first evening was the warm-and-fuzzy celebration of Michelle Obama. Then came Hillary Night. Throughout both evenings, some shots had been taken at George W. Bush and John McCain, but no real fusillade had been launched against the two. (Ohio Governor Ted Strickland had a good line on Tuesday when he quipped, "It was once said of the first George Bush that he was born on third base and thought he'd hit a triple. Well, with the 22 million new jobs and the budget surplus Bill Clinton left behind, George W. Bush came into office on third base, and then he stole second.") This consultant noted that four years ago he had argued against the stay-positive approach of John Kerry's convention. The Kerry crew's decision to not pummel Bush throughout the four-day convention is now regarded by many political pros as a major error. And this consultant was worried that the Obama camp was repeating history. "We've lost two nights," he said.

He knew that on Wednesday night, Senator Joe Biden would take after McCain. That's what veep candidates do. They play the attack dog. And every Democrat and journalist in Denver was expecting Biden to do so with enthusiasm. But regardless of how well Biden would do in this role, it did seem that the Obama campaign had relegated its assault on McCain to something of an "attack hour," rather than integrate it fully into the convention's narrative. (And Biden's attack would have to compete for attention with Bill Clinton's much-anticipated speech that night.) Though the Obama campaign did have to go through several compulsory exercises on the first two evenings--"humanize" Michelle, hail Teddy Kennedy, and pacify Hillary Clinton--it's not hard to imagine an alternative schedule that would have featured speakers or films that ripped into McCain to make the point that this election presents a fundamental choice and that a vote for McCain would be one damn serious mistake.

Obama did win the nomination by promising to rise above partisan potshots. But not every shot has to be a cheap one. The Republicans and their allies, of course, are doing what they can to make Obama seem like The Other. They question the American-ness of Obama and his wife. They lie about his tax plan. Their goal: to delegitimize Obama. The Obama campaign should not follow the GOPers into the gutter. But it does need to persuade those I-don't-know-yet voters that McCain is not only an ex-POW and self-proclaimed maverick but a fellow who--due to his conservative policy positions, connections to corporate lobbyists, cluelessness about the Internet, combustible temperament, eagerness for military confrontation and more--would be a bad president for the country. Up to now, much of the Obama campaign's assault has focused on tying McCain to Bush. (Hillary Clinton's one zinger against McCain played off this point.) But this line of attack will only go so far. On Election Day, voters will be deciding between Obama and McCain. For Obama to win, voters will have to believe McCain himself--because of his own views, his own traits--is dead wrong for the job.

Has the Obama campaign blown it? Hyperbolic questions like this cannot be answered until after the votes are cast and counted. But let's consider another question: will the Republicans at their convention next week begin with two soft nights and not try to rip the hide off Obama from the start? Perhaps. But if I were an Obama adviser, I wouldn't count on that.