WASHINGTON -- Something strange is happening in this strangest of all presidential contests. The longer it goes on, the less we know about what either of these men would really do if he were in the Oval Office next year.

John McCain and Barack Obama have been asked twice -- once in the Mississippi debate and again on Tuesday night -- what their priorities would be. McCain flat-out refused to choose, arguing that the United States can do it all. Obama mentioned energy, health care and education, but did not acknowledge that he might have to choose among them.

Similarly, they declined to spell out what sacrifices they might have to ask Americans to make, beyond moderating their energy use or easing their demands for Washington-financed projects.

It was a stunning rejection of reality. This nation is mired in two wars it does not know how to end. It is struggling to escape the worst economic crisis since the Great Depression. The federal government is staring at record deficits, with no plausible plan for financing the retirement and health care needs of a giant generation of retirees. Our transportation and education systems need help, and we are dependent on other countries for the energy we use.

In the face of all this, Obama and McCain are stubbornly repeating promises they made in happier times -- tax cuts for all, new health benefits, big government-financed projects.

To govern is to choose, and next year, the trade-offs will be much tougher than usual because of the mess the Bush administration is leaving behind. At a moment when few Americans can muster much confidence in the leaders in Congress or the White House, McCain and Obama have used two of their three debates -- three hours when they had the attention of millions of voters -- to conceal more than they revealed about their agendas.

That is why these debates are the opposite of game-changers. The campaign is being driven by real-world events, not the words of the candidates. Obama has moved ahead, by every measure, in part because voters consistently rate Democrats over Republicans on the big domestic and economic issues, and in part because his hard-working supporters are changing the electorate with their registration and voter-turnout campaigns.

The candidates did do the country -- and themselves -- one favor by avoiding the personal attacks that their campaign associates had been making for the previous five days. It was a relief to be spared more discussion of Bill Ayers and the Keating Five.

But the frustration that is growing stems from their mutual reluctance to talk candidly about the situation one of them will inherit.

If either of them has a clue about what to do to help stabilize this tottering economy, he is keeping it to himself. McCain threw out the notion of buying up distressed mortgages, but in such an offhand manner that no one could tell what he meant -- or what it would cost.

Even when they have been specific, it is hard to credit their words. Both have promised sweeping tax reductions, targeted to different populations. But neither has given any indication how the promises will stand in the face of the massive new spending needed to rescue embattled financial institutions.

Absent any reliable information about their programs, voters must fall back on an examination of their records and characters. The records are admirable, but sketchy, because neither of them has had to assemble or direct or motivate a large administration. Their executive abilities are untested.

By contrast, we have every reason to admire their characters -- including their willingness to deal seriously with members of the opposite party. The good news is that both these men are willing to listen.

It may be that we will not know what policies we're getting until one of them takes office. But I was struck by the survey of economists reported in the current issue of The Economist, the London newsmagazine that covers America so well. It found much greater confidence in the economic views and advisers of Obama than McCain. The 142 respondents included far more Democrats than Republicans. But even among Republicans, the Obama team was rated superior -- and among the unaffiliated, the choice was overwhelming.

That is less satisfying a measure than the candidates themselves could provide, if they were more candid. But it may be the best we can get.

David Broder's e-mail address is davidbroder@washpost.com.