Monday night, before President Barack Obama and challenger Mitt Romney debated, a new Washington Post/ABC poll showed how treacherous a world this is — for candidates.

Obama’s once-commanding lead over Romney on foreign affairs had dropped to 3 percentage points (49-46). His lead on handling terrorism was 1 point (47-46). His advantage as commander-in-chief? Also thin (48-45).

The findings, in line with other surveys, made this another crucial debate in a series like none before it: Either man could emerge from this near-tie.

Those who thought Romney would look more belligerent than knowledgeable saw none of that. But they also saw a president who projected confidence in his management of the U.S. role in world affairs.

At several points, the challenger didn’t challenge: He didn’t draw the huge distinctions with Obama that he has on economic issues at home. On topics from Afghanistan to Pakistan to China to the use of drones, the two offered consonant themes.

Romney’s difference with Obama on Iran was a matter of degree. He would have pursued tougher sanctions early, he said. The candidates in effect reaffirmed their different tolerances — Obama again vowing not to let Iran build a nuclear bomb; Romney letting stand his pledge not to let Tehran reach the capability to build a bomb.

On Israel, the distinction struck us as semantic: Asked if an Iranian attack would draw a U.S. strike, Obama said he would “stand with Israel” without elaborating on that metaphor. Romney concurred, adding that he meant “not just diplomatically” but “militarily.”

A discussion on America’s global role separated the candidates … a bit. Romney essentially argued that by avoiding stronger leadership roles, the U.S. risks being buffeted by events rather than molding them: “Nowhere in the world is America’s influence stronger than it was four years ago.”

Romney, however, had trouble spelling out by what steps he would more forcefully assert U.S. leadership. Obama challenged Romney’s credibility — “I know you haven’t been in a position to execute foreign policy” — a reminder that only one of these men has had the responsibility for the last four years of representing this nation to the world and protecting this nation from harm.

Obama warned that arming Syrian rebels risks putting weapons into the wrong hands. Romney countered that the Syrian crisis presents the U.S. with an opportunity to undermine a regime that is Iran’s strongest ally in the region. But Romney stated that he didn’t want the U.S. military involved in Syria.

Both men stated that the U.S. military will leave Afghanistan in 2014 — essentially agreeing on a timetable.

Romney contrasted the initial hopes of the Arab Spring with resurgent conflicts in the Mideast. Early on, Romney congratulated Obama for attacks on Osama bin Laden and other terrorists before adding, “We can’t kill our way out of this.”

His suggestion: greater emphasis on education, gender equality and other initiatives “to get the Muslim world to reject extremism on its own.”

The brief discussion on the killings of four Americans in Benghazi, Libya, on Sept. 11 didn’t break new ground. Neither candidate went past familiar talking points.

This magnificent series of debates ended with agreeability and relative calm: Two candidates, assuring Americans that each of them would be careful about extending U.S. military might around the world. Obama and Romney wanted to convey that each would avoid blundering into new wars. Both made convincing cases.

In only a few days, we’ll know who made not only the case, but the sale.

Editorial by the Chicago Tribune