An independent research group that tracks the influence of money in politics has conducted an analysis of oil industry contributions to members of Congress supporting the pipeline.
The Obama administration has been accused of hounding the scientist so it can open up the fragile region to drilling by Shell and other big oil companies.
What are the dangers of pumping gritty, thick crude at high temperature and pressure through a pipeline with walls less than half an inch thick across vital sources of groundwater?
Browner's exit reinforces concerns Obama is preparing compromises on his once-ambitious green agenda to try to build working arrangement with Republicans.
