just a few reasons....
EnvironmentSestak voted for the Waxman Markey American Clean Energy and Security Act (Cap and Trade) program.<18> He is the only Pennsylvanian congressman to have a 100% rating from the League of Conservation Voters and PennEnvironment. He was also endorsed by the Sierra Club in his 2008 Congressional re-election. He voted for the Renewable Energy and Energy Conservation Tax Act of 2007 and the New Direction for Energy Independence, National Security and Consumer Protection Act. He was also an original co-sponsor of the Climate Stewardship Act (H.R. 620) and the Safe Climate Act.<19>
Gun rightsSestak supports gun control and has a 100% rating from the Brady Campaign to Prevent Gun Violence<20> and an F rating from the National Rifle Association.<21>
Sestak has called for the reinstatement of the federal ban on assault weapons.<22>
HealthcareSestak credits his support for health care reform as to "pay back" the country that provided him and his family health care while he was in the Navy (the TRICARE program), especially for treating his daughter's brain tumor.<23> He supports state-provided preventive care and voted for the CHAMP Act. Sestak originally co-sponsored the Medicare Prescription Drug Price Negotiations Act, the Caroline Pryce Walker Conquer Childhood Cancer Act and co-sponsored H.R. 3800, which establishes a public-private Partnership for Health Care Improvement. He also announced the Pediatric Cancer Caucus, which he will co-chair.<24> He is also a member of the Autism Caucus, Diabetes Caucus,<25> 21st Century Health Care Caucus, Congressional Mental Health Caucus, Nursing Caucus, and Cystic Fibrosis Caucus.<26>
LaborSestak is an original co-sponsor of the Employee Free Choice Act and supports the original version that includes card check. He created the Labor Advisory Committee to address the challenges facing working families in his district.<27>
Medical marijuana
Sestak showed support for states to determine their own destiny regarding medical marijuana by voting for the Commerce, Justice, Science, and Related Agencies Appropriations Act of 2008, which would have barred the Department of Justice from preventing the implementation of state laws regarding the distribution, possession, and cultivation of medical marijuana. The bill was defeated 165-262.<28>
http://en.wikipedia.org/wiki/Joe_Sestak