AS THE PRESIDENTIAL campaigns officially kick off, with the Republican convention week and the Democrats assembling the week after, many voters are exasperated and tuning out.

The unrelenting ugliness of television ads is one cause, as those of us with the mixed privilege of living in a swing state such as Virginia (or in its media market) know well. But there’s also a sense of disappointment in the candidates — a sense that they are smaller, and their campaigns are smaller, than the issues and challenges facing the country.

In the case of presumptive Republican nominee Mitt Romney, part of what underlies the unease is an uncertainty about core beliefs. Every politician will change positions over a career; you’d worry if he or she didn’t. But few have covered as much ideological ground as the former Massachusetts governor: on abortion, stem cell research, health-care reform, gun control, immigration, gay rights, climate change and more.

It may seem a small thing, but when a man who’s been hunting twice can blithely say that he’s been a hunter “pretty much all my life,” it makes people wonder what is real. His attacks on primary opponents Rick Perry and Newt Gingrich for revealing even a sliver of pragmatic concern for undocumented immigrants suggested an ethos of winning at any cost and a deficit of principle. The sketchiness of his policy proposals since then only aggravates the concern.

In President Obama’s case, there’s a different sort of disappointment. The country has a pretty good sense of the man by now and generally likes him. But he has not, as many had hoped, fully inhabited the presidency, in the sense of rising above the pettiness and partisanship that he diagnosed so eloquently before assuming office.

Simpson-Bowles is the shorthand for the most commonly cited failing in this sphere, referring to the bipartisan budget deal that Mr. Obama commissioned but then could not bring himself to embrace. That was emblematic of a reluctance to provide leadership, abroad (with Syria, for example) as well as at home.

Is there hope for something bigger, more edifying, more statesmanlike, from the candidates? We’d like to think so.

One reason is that both candidates are men of toughness and intelligence. Mr. Obama has proved as much in office. In the teeth of an economic gale, he helped stabilize the nation’s finances and succeeded in extending health-care coverage to millions of uninsured. His stewardship of foreign affairs, while disappointing in numerous ways we haven’t hesitated to mention, has been sober and thoughtful.

Mr. Romney has a heavier burden of proof, but he comes with an accomplished résumé and an understanding of how to get things done. His selection of Rep. Paul Ryan (R-Wis.) as his running mate, much as we take issue with Mr. Ryan’s fiscal priorities and even his arithmetic, bespeaks an openness to debate entitlement reform that the country badly needs.

And the country needs a serious campaign; it is facing life-or-death questions. Is al-Qaeda dead, or nearly so, leaving the United States free to move on to other challenges, such as China’s rise, or does Islamist radicalism still present a breeding ground for existential threats? Can the United States influence whether the Arab Spring evolves toward greater democracy or toward theocratic rule and sectarian conflict? Can Iran’s nuclear ambitions be cooled peacefully, and if not, do they really justify a war? If so, why, and what would the consequences be?

Do the candidates believe that the United States remains the world’s indispensable nation, and what does that mean in Syria or the South China Sea? What would either candidate expect to achieve in Afghanistan?

We are facing existential questions at home, too. Is the kind of economic growth the country enjoyed in the 1960s and 1970s gone for good, or can it be rekindled? Can poverty be ameliorated and prosperity more evenly shared? As the nation’s population ages, can the government right-size itself and the entitlements it has promised, or will political dysfunction produce growing debt and eventual decline? These challenges begin not on Inauguration Day but the moment the polls close, when Congress must confront the looming fiscal cliff.

So far, the campaigns have focused instead on Mr. Obama’s “you didn’t build that,”Mr. Romney’s tax returns and, most recently, Rep. Todd Akin’s “the female body has ways to try to shut that whole thing down.”

We don’t dismiss these as distractions. The differences between the candidates on abortion are important considerations, as is the anti-science or pseudo-science strand of the Republican Party typified by Mr. Akin’s remarks. Mr. Romney’s secrecy on his tax returns and his campaign bundlers says something about his attitude toward the public that the public would be foolish to ignore. The debate over government’s role in the economy is important, too, and potentially useful.

But such a debate isn’t sufficient. Yes, Mr. Obama will, and should, make familiar Democratic arguments for spending more on roads and schools. Mr. Romney will, and should, make familiar Republican arguments for taxing and regulating less. Mr. Obama will tout wind, Mr. Romney will preach oil.

Neither, though, will be able to lead the country on such a narrow partisan basis. The one November outcome we can almost definitively rule out is a mandate election, in which one party overwhelms Congress and the White House in a landslide. Politics will force whoever wins to search for compromises with the other side.

Even more important, the nature of the problems will mandate such a search. Saving Medicare will require a combination of market forces and regulation. Avoiding national bankruptcy will require higher taxes and scaled-back benefits. A rational climate-change policy will end up encouraging both wind and natural gas.

A candidate who can lay the groundwork for those kinds of solutions over the next two months might spur voters to start listening again.