Today’s debate mostly proved that point. When the Republicans vying to be their party’s 2008 nominee gathered for their fourth debate in as many months, perhaps the only distinguishing difference from other forums held so far was the location—Iowa—and the number of men on stage—now eight, since Jim Gilmore dropped out last month.

No doubt there were subtle changes among the GOP field, mainly in terms of performance. After some shaky moments in a few of the earlier debates, Mitt Romney came off confident and smooth—delivering perhaps the best line of the day, a dig at Barack Obama’s foreign policy moves last week. “He’s gone from Jane Fonda to Dr. Strangelove in a week,” Romney declared. (The line was clearly not off the cuff. Upon delivery, his campaign almost instantaneously zapped reporters covering the debate a link to a YouTube video of the crack.)

The second tier hopefuls kicked it up a notch too—with Sam Brownback, Mike Huckabee and Tommy Thompson all coming off as a little bit more aggressive than they had in previous debates. John McCain, on the other hand, seemed tired and sluggish early on and relied almost too much on lines he’s used many times before. For a guy known to be fired up and energetic at town hall meetings across Iowa and New Hampshire, McCain comes off as a different person at the debates. Given his weakened position these days, that’s not doing him any good.

But in a race where substance should trump style—well, it just didn’t. Anyone hoping to learn anything new—anything at all—about the Republicans who aspire to succeed George W. Bush ended the 90-minute debate mostly empty handed. That is, unless you were surprised to hear that Duncan Hunter once considered running as a Democrat back in the day. Who knew?

On the biggest issues in the race, there was little to no movement among the frontrunners and the men chase them. On Iraq, Romney and Rudy Giuliani remained in lockstep with John McCain in opposing a drawdown of troops in the region. Asked if there were any disagreements between them and McCain, Romney replied, “I think we’re pretty much in the same place.”

Yet it continues to be McCain who seems to bear the burden of urging Americans to be patient over the troop surge and convincing them that withdrawal is not a good idea. Several times on Sunday, McCain diverted from questions on other topics to deliver an impassioned defense of the war—a risky gamble, especially here in Iowa, where poll numbers in support of the war are among the lowest in the country. “This is a seminal moment in American history,” McCain said. “I’m going to be judged by history, not by public opinion polls.” Still, he added, “I believe that we can and must prevail. We’ve got the strategy, and the general that can do it. Give us some time for it to succeed.”

Interestingly, the candidates tried to walk a delicate line on the war position and Bush. While the hopefuls were incredibly critical of Bush and his handling of the war during a June debate in New Hampshire, they kept their powder largely dry this time, in spite of the fact that Bush seems even more unpopular than he was two months ago.

At the same time, they didn’t hide their criticism of his relationship with Dick Cheney. Asked if his VP would be as powerful as Cheney, McCain replied, “I would be very careful that everybody understood that there’s only one president.” Brownback was less subtle, saying that Bush had “over-relied” on Cheney.

Romney, who too has tried to walk a fine line between criticizing the president while also wooing his supporters, defended the White House. “It’s been very popular lately for people across the country to be critical of the president and the vice president,” he said. “And I know they make mistakes. But they have kept us safe these last six years. Let’s not forget that.”

There were a few fireworks early in the debate over abortion, but it’s unclear the sparring will change anything about the race. With the Ames Straw Poll just a week away, Brownback has been hammering Romney over his stance on abortion in hopes of scoring points with Iowa voters.

In ads, Brownback has attacked the former Massachusetts governor as a flip-flopper on the issue," citing Romney’s “pro-abortion” policies while in office. Asked about the ads, Brownback defended them as “truthful” while Romney decried them as inaccurate and “desperate”—though he admitted that he had taken an “effectively pro-choice” position at the time. “I get tired of people that are holier than thou because they’ve been pro-life longer than I have,” Romney grumbled.

But when ABC played a video of Romney criticizing Giuliani on the same issues, he played nice, refusing to criticize the former mayor for his old positions. “I think I have a better perspective on his views now,” Romney said. “I’d rather let him speak for him[self], his own positions.”

A presidential candidate who would rather let his opponent explain where he stands on issues? Wow. Maybe this debate wasn’t so typical after all.