Here we go again. Every election cycle we reach this point when television news reporters pull out all the same old supposed zingers from past U.S. presidential debates to warm up the audience for the imminent round of faceoffs and gaffes.

I know. I've done it myself many times — most recently, Monday night.

Hear Ronald Reagan tell Jimmy Carter, "There you go again."

See George H.W. Bush check his watch before answering a voter's question.

Look at John Kennedy in 1960. Just look at him. Enough said.

I've used them all and, like many of my colleagues, I've noticed that, with the exception of 1976, when Gerald Ford emphatically and absurdly declared that Eastern Europe was not, and never would be, dominated by the Soviet Union, the memorable moments of past debates seem invariably to be merely moments of style not substance.

This seems so obvious that it barely merits comment any more.

And while it is true that television is a medium better suited to passion and action than to thoughts and ideas, that is not what diminishes the value of these television debates.

For one thing, television doesn't actually prohibit thoughtfulness. Thoughts and ideas do, sometimes, squeak through the lens and into our brains.

Nor is there anything inherently wrong with catching a glimpse of the inner workings of someone who seeks to be the "leader of the free world," as many Americans like to say.

Most of us will admit that we make our voting decisions in both our heads and our guts.

So what reason is there to pretend that there is no value in seeing a presidential hopeful thoroughly embarrassed, humiliated and struck dumb by something his opponent said straight to his face in front of a national television audience?

That's when we see who is soft in the middle, as Margaret Thatcher was wont to say.

Or, as Marvin Kalb more politely puts it, "television is an extraordinarily revealing technology."

Does character matter?

Kalb was an NBC news correspondent who had the rare experience of actually participating in a presidential debate as part of a panel of journalists, in 1984.

"It gets through the outside and it gets into the inside and it does show more times than not the kind of human being that might end up being the president of the United States," he says.

And that's all fine, it matters, we get that. But does it make a difference?

What has really diminished presidential debates in recent years is everything else that happens in a campaign.

I'm thinking here of the waves of television ads that cost hundreds of millions of dollars and begin rolling into selected markets months before people have turned their minds to voting.

Or the court decisions that opened the campaign trail to corporate spending on a scale that mocks any semblance of regulation.

Or the voter targeting tactics that divide up the electorate into smaller and smaller slices to receive ever more precisely designed and "personal" campaign messages, which beggar the concept of a "national interest" beyond self-interest. All of those things are how campaigns are now won.

It's still true that the individual candidates matter. But by the time we get to this debate stage, the course of the election has been pretty well set by all that's gone before.

And that's usually an unfortunate thing for the challenger in the race, as number cruncher Nate Silver has noted in his New York Times column of why campaigns rarely break towards the challenger this late in the game.

In this race, there is little doubt that the candidate who's most uncomfortable with that fact is Mitt Romney.

U.S. President Barack Obama and Republican rival Mitt Romney will face off Wednesday night in their first debate. (Kevin Lamarque/Brian Snyder/Reuters)

"People don't know a lot about him," says political analyst Bill Schneider of The Third Way, a Washington think tank. "All they know is he's a rich guy. And he's got to use this debate to kind of change his image.

"He has to actually downright win this debate to change the logic of this campaign because, right now, as every day proceeds, closer and closer to election day, he's doing worse and worse."

But would a Romney "win" tonight be a game changer?

The last time a challenger faced an incumbent in a series of presidential debates was 2004 when John Kerry took on then-president George W. Bush.

The day after the first debate, Gallup released a survey of how voters had responded.

Fifty-three per cent said they thought Kerry had won the debate; only 37 per cent said Bush had won.

The second and third debates went much the same way.

The following month Bush was re-elected president with 50.7 per cent of the vote.