What do impact do you want the prioritization to have? (SM doesn't assign contacts. They are in a list. The user can pick them in any order.)
You can tag contacts with "Priority" and filter to only see those. Or you can tag some with "Priority 1" and some with "Priority 2" etc. and filter to show the P1's or show the P2's etc. ...so you can put priorities in the tags and using filters you can show users certain priorities.
Tod