The VP main role until the president dies is to be the tie breaking vote in the senate.Thats EXACTLY what the VP is for....why do you think there all those rules about them not Flying in the same plane ,not eating the same meal and shyt like that...so that the president can get a little blowed /drunk once in a while and someone will still be watching the wheel .
Constitutionally outside of being backup for the president if he dies, that is he only explicitly defined role.
The overly involved VP ala Cheney is not normal or what was intended.