Sec. of Interior Ken Salazar favored offshore drilling

While researching my timeline of the BP oil disaster in the Gulf of Mexico, this is what I learned about Ken Salazar, Obama's Secretary of the Interior. Salazar's department oversees the MMS. Throughout 2009 MMS not only failed to respond to whistle-blower complaints regarding the safety BP's largest deepwater rig in the Gulf of Mexico, it blocked the release of evidence (see timeline for details): 

JAN 2009:  President Obama appoints Ken Salazar (photo) Secretary of the Interior, overseeing MMS, the federal government oil industry regulator.  Previously, Salazar supported the nomination of Gale Norton to Secretary of the Interior, President George W. Bush's controversial first appointee who preceded Salazar as Colorado Attorney General. Soon after arriving in the Senate, Salazar generated controversy within his party by introducing Attorney General nominee  Alberto Gonzales and sitting by his side during Gonzales' confirmation hearings. In August 2006, Ken Salazar supported  Joe Lieberman in his primary race. In 2006, Salazar voted to end protections that limit offshore oil drilling in Florida's Gulf Coast.  In 2007, Salazar was one of only a handful of Democrats to vote against a bill that would require the United States Army Corps of Engineers to consider global warming when planning water projects. 

Why hasn't Ken Salazar resigned already?