WASHINGTON—The financial crisis has turned into a tryout of sorts for the next president, an unexpected chance for Barack Obama and John McCain to shine—or stumble—just as most voters are deciding whom to back.

At times like these, when the real world intrudes on the carefully controlled campaigns, the spotlight shines even brighter on the presidential candidates. Their responses and postures may tell voters more about how they would act if elected than allegations of lies in advertising and quips about lipstick on pigs.

Both have got some work to do.

“People are confused, they’re scared and they’re angry, and neither of these guys is providing the security, maturity and experience to be able to calm those fears,” says Joe Gaylord, a Republican consultant. “If these candidates can rise out of their campaign mode and get into the president-of-all-the-country mode, people would feel more comfortable.”

The trick for each is not to look like he’s trying to score cheap political points off a crisis.

Last month, Russia’s invasion of Georgia provided a taste of how outside events can affect the presidential race. McCain seemed to hit his stride more quickly than Obama. In the financial meltdown, the opposite has been true.

Between now and Nov. 4, any number of other domestic or foreign events could intervene. For now, all attention has swung to the financial crisis that has spread worldwide. Despite Friday’s major actions by the federal government, even more economic troubles could be ahead, putting additional pressure on both Obama and McCain to map out solutions and prove they can handle adversity.

Both men are treading carefully as they use the Wall Street chaos not only to sell their economic plans but also to try to sound and act presidential before a nervous nation seeking leadership.

On Friday, Obama struck a stately stance as he acknowledged “difficult days” and said: “This is not the time for fear or panic. This is a time for resolve and for leadership. I know we can steer ourselves out of this crisis. That’s who we are. That’s what we’ve always done as Americans.”

After fumbling earlier in the week, McCain’s remarks had a more partisan edge. He claimed Obama “profited from this system of abuse and scandal”—even as he said: “It took members of both parties to get America into this mess, and it will take all of us, working together, to lead the way out.”

For now at least, the campaigns have returned to issues and substance after weeks of clashes over personalities and characters. Each candidate has accused the other of lying in campaign commercials, and there was a dispute over whether Obama was insulting GOP vice presidential nominee Sarah Palin when he used the phrase putting “lipstick on a pig.”

“The real world was always going to re-exert itself because there are big problems,” said Bob Shrum, a Democratic veteran of several presidential campaigns. “Voters were having a lark but now they’re saying to themselves, what’s going happen to me and my life and my family in the next four years, and who is best to lead the country.”

Thus, mistakes are magnified.

Take McCain.

As markets tumbled Monday following the bankruptcy of Lehman Brothers and the takeover of Merrill Lynch, the Arizona senator—who has acknowledged that economics is not his strongest suit—made his oft-repeated assertion that “the fundamentals of our economy are strong.” Democrats swiftly assailed him, tagging him as out of touch and a continuation of President Bush.

McCain has spent the days since trying to explain what he meant and, with a more dire tone, letting voters know that he feels their pain. Now, he’s calling the financial woes “one of the most severe crises in modern times,” says he would fire the Securities and Exchange Commission chairman if he were president, and advocates creating a special trust to help strengthen weak institutions.