What could cause a 1999 Saturn SW2 to undercharge?

Answer:
Weak alternator?
Bad Voltage regulator?
Alternator belt slipping?
Note: There are comments associated with this question. See the discussion page to add to the conversation.
First answer by Baldfatguy. Last edit by Baldfatguy. Contributor trust: 2032 [recommend contributor recommended]. Question popularity: 4 [recommend question].