What does Ellis mean when he says that "Madison's position on slavery captured the essence of what might be called 'the Virginia straddle'"?

This would mean riding both sides of the fence on the argument of slavery. On one hand, they believed the abolishment of slavery to be inevitable....... on the other hand, ending slavery prematurely without plan might cause more problems than they could handle at the time. Everyone was aware of the "shameless indecency" of slavery, but no one ws ready to sit down at that time and make it an issue.