Integrity is the commitment to live by one's ethical and moral principles, regardless of the circumstances. Of course, persons of integrity may change their position on certain issues when new information is brought to their attention.
There is perhaps no better group of individuals who clearly manifest integrity (or lack thereof) than politicians, whose job depends totally on the whims and interests of their constituents. While some abide by their principles, whether liberal or conservative, many (if not most) twist in the wind of public opinion and pressure.
Currently, a group of Republican Congressmen, most of whom have strongly criticized and openly despised Donald Trump in the past, are vying for the opportunity to be his running mate. Though Trump has not changed, they have abandoned their own principles, willing to support his dangerous policies. By doing so, they demonstrate their personal lack of integrity.