It calls us to do better and to be better. That happens, in part, because a great leader is willing to be a role model for us. So often in the Scripture, we see leaders calling people to take a look at them. Role models not only tell you to do something, but show you how to do it. That does not mean, however, that in a democracy like ours, we should elect only perfect people.
Perfect people are in pretty short supply.
In the Bible we find a multitude of flawed leaders. Great King David was only a boy when he killed another human being, the Philistine Goliath. While he was king, he had an adulterous relationship with a married woman and tried to cover it up by plotting and scheming to have the woman's husband killed. Peter, the apostle Jesus chose to lead the church, on the night of the Master's arrest, denied three times that he knew our Lord, and like any good modern politician, he waffled on the issues. When he was with the other apostles in Jerusalem, he had one view on a certain matter, but when he was on the road with Paul, he held an opposite opinion on it.