SOUTH BEND - Mayor Pete wasn’t known as a foreign policy expert while serving as South Bend’s mayor. But then Sen. Bernie Sanders never has been known as a foreign policy expert while serving for so long in the Senate.

And the current president doesn’t exactly demonstrate expertise in relations with foreign nations, whether they be friends or foes.

So, it will be interesting if foreign policy is — as it should be — a major focus of the Democratic presidential debate at 9 p.m. (ET) Tuesday at Drake University in Iowa. It will feature six candidates, former Vice President Joe Biden, former South Bend Mayor Pete Buttigieg, Minnesota Sen. Amy Klobuchar, Vermont Sen. Bernie Sanders, billionaire executive Tom Steyer and Massachusetts Sen. Elizabeth Warren. It comes as U.S. Sen. Cory Booker withdrew fron the race Monday morning after failing to make the debate stage.

The only one of the debating Democratic candidates with real foreign policy expertise is Joe Biden, the former vice president who long was the top Democrat on the Senate Foreign Relations Committee back when it was powerful and prestigious. He knew the world. The world knew him.

Will this be Biden’s time to shine, talking about a subject he knows better than any of the other debaters? Maybe. He has an advantage. Maybe not. His long record in foreign relations, including joining in the initial strong national support for the war in Iraq, will be scrutinized. In the case of the mistaken Iraq war, it will be criticized.

Will this be Pete Buttigieg’s time to show that he — the only one of the top contenders with military service, with active duty in Afghanistan — has a reasoned, measured approach to the crisis with Iran and other dangers around the world? Maybe. He was one of the first Democrats to respond directly and carefully to the crisis after the killing of a top Iranian commander. Maybe not. He will face challenges that a mayor of South Bend develops expertise only in relations with places like Mishawaka.

Will this be the time for Sanders to demonstrate he knows about the world, not just that he “wrote the damn bill,” a bill now with no chance of passage? Maybe. He certainly has views on avoiding conflicts abroad. Maybe not. He seems to want always to get back to his talking points on “his” issues, nothing else.

Will this be the time when one of the others, Sen. Elizabeth Warren or Sen. Amy Klobuchar, surges with focus on something as important as war and peace? Maybe. Warren needs to recover after slipping in the polls. Klobuchar needs finally to move up to top-tier contender. Maybe not. Will they, instead of looking up to the challenge, look down again into a wine cave?

The debate could deteriorate into a circular firing squad, with squabbles over things of little significance turning off viewers and enhancing President Trump’s re-election prospects.

But the opportunity is presented to rise above a wine cave and focus on the significant role of the president in this dangerous world — dealing with Iran, North Korea, Afghanistan, Syria — and Putin.

The opportunity comes as a result of a scary situation, the prospect of military conflict with Iran and elsewhere in the Middle East after the killing of Gen. Qassim Suleimani, loathed here, a hero there.

The debate, the seventh, will be the most important yet. It comes with the field finally narrowed to serious contenders and with the Iowa caucuses just three weeks away.

It comes with a recent CBS poll showing the Iowa race so close that Biden, Buttigieg and Sanders are tied, all with 23 percent support.

It comes with other poll results showing President Trump edging up in approval ratings, with voters split evenly on whether he should be removed through conviction on impeachment charges in the Senate.

Conviction won’t come. Acquittal in the Senate could help him.

Trump’s handling of the crisis with Iran, however, could diminish his chances. Or improve them, if the Democratic opposition doesn’t emerge as having a better, safer way to deal with foreign relations on issues of war and peace.

Jack Colwell is a columnist for The Tribune. Write to him in care of The Tribune or by email at jcolwell@comcast.net.