Pssst. Don't spread it around too much, because there's still a month to go and I don't want to jinx things - but substance is in this year. You, I know, think US presidential elections are always decided by silly or superficial or out-and-out false representations and aspersions. Al Gore sighed too much in a debate and wasn't the sort of fellow you'd like to have a beer with. George W Bush never sighed once, as far as anyone could tell, and was the sort you'd like to have a beer with (even though he didn't drink beer - I never quite sorted that one out). John Kerry seemed so French and effete. He windsurfed. And he didn't save all those men during the Vietnam war. How could he have, really, being so ... French and effete and windsurfy?

Little glimmers of substance have usually shown through. In 2004, for instance, a still-significant percentage of American voters remained jittery about a second large-scale terrorist attack on US soil. Bush ran as the man who had prevented that from happening and argued that he was more trustworthy on this matter than Kerry. And Bill Clinton withstood an intensive barrage of over-the-top attacks and stayed focused on the economy (he was helped along by third-party candidate Ross Perot's hefty 19% of the vote).

Superficialities and attacks, though, usually dominate. We understand this. In fact, more than a few liberals have spent the last four years trying to persuade Democrats to be every bit as superficial and nasty as the Republicans are at election time. But this year, something feels different. Voters are actually paying closer attention to issues.

It is the result, no doubt, of the US being in terrible shape right now. It tends to focus the mind. The economy is terrible. The stock market is terrible. Indicators of general societal wellbeing, like healthcare and pensions, are terrible. Our standing in the world is terrible. The conditions in Afghanistan are terrible. The situation in Iraq is improved but was so terrible for so long that people just basically want out.

We are a country in decline. The decline is the result of the policies of the last eight years. Everyone outside of hardcore conservatives knows this. No candidate for president can utter the sentence "we are a country in decline". America's central myth about itself is that, unlike Rome or Austria-Hungary or (sorry) an earlier Britain, we are impervious to time's vicissitudes and will always be numero uno. People now are worried that underneath that bravado, maybe we won't be.

And so, substance matters. The public responses to the financial meltdown and the first two debates make this evident.

When the Wall Street crisis hit, John McCain erupted with lots of bluster about how he was going to crack down on the fatcats and the greed heads. He "suspended" his campaign to return to Washington to handle the problem. He called Barack Obama green and a hypocrite. In other words, he was superficial and nastily aggressive in precisely the way that usually works in presidential campaigns. But he lost the argument badly and irrevocably - polls before the Wall Street crisis showed him closing the gap with Obama on the question of who can better handle the economy. That gap is now wider than ever, and will probably remain that way.

Obama, by contrast, stayed calm, didn't attack McCain's stunt and at press conferences listed the specific items he needed to see in the bail-out bill. He was talking with congressional leaders and the treasury secretary about these substantive points. To the Americans who were paying attention, the distinction between the two candidates was clear.

Likewise with the debates. McCain had more zingers and one-liners than Obama did and generally speaking was the aggressor that night. And Sarah Palin, with her repeated winks at the camera, had far more of a folksy, I'm-just-like-Joe-Sixpack approach than Joe Biden did. One-liners, aggression and emotive warmth are supposed to win these contests, we are told, and they usually do. But literally every poll I've seen shows that voters think Obama and Biden - who were direct and substantive and between them barely said one zingy or folksy thing - won the debates, and handily so.

The Republicans can't win on substance. Most of their positions are too unpopular. They know this, and this is why they lie, like Palin did during her debate, about leading the state of Alaska to divest of investments that could benefit the Sudanese government. It turns out that her administration opposed such divestment when it mattered and that she finally told a legislator or two she was for it - after it was too late for the legislature to act. That's not substance. It's substance abuse.

So in this closing month, they will do what they know how to do. Republican operatives told the Washington Post last Saturday that they will spend the remaining days attacking Obama's character and past associations. Meanwhile, independent conservative groups are bound to spread all manner of disinformation - about how al-Qaida wants Obama to win and how, if the Democrats capture the White House, they'll outlaw the Ten Commandments.

We've seen lies like these work before. But what we haven't seen before is basically 80% of American adults feeling this miserably about their country. If there's ever going to be a circumstance when voters stay focused on the things that matter, this ought to be it.

• Michael Tomasky is editor of Guardian America

michael.tomasky@theguardian.com