First, the Bush/Group of 8 position:
The Pain of the G-8’s Big Shrug
All the genocides of the last 100 years have cost only 10 million to 12 million lives. In contrast, every year we lose almost 10 million children under the age of 5 from diseases and malnutrition attributable to poverty. Make that the priority, not Darfur.
There are also practical arguments, for genocide can create cycles of revenge and displacement that make it far more destabilizing than any famine or epidemic. The Darfur genocide may well lead all Sudan to fragment into civil war, interrupting Sudanese oil exports and raising oil prices.