WASHINGTON — Sen. Bob Casey, D-Pa., announced Thursday that he has been diagnosed with prostate cancer and will undergo treatment. He was re-elected in 2012 and 2018, even as the state swung between Republicans and Democrats in the presidential contest. Casey has proven to be a moderate in the Senate, largely staying out of the spotlight but joining Republicans and other Democrats to negotiate bipartisan legislation. He entered Congress with a pro-gun rights position that distinguished him from other Democrats, but he has since helped to negotiate legislation like background checks for gun purchases. Casey also staked out an anti-abortion position when he entered Congress, but joined Democrats last year in efforts to enact some protections for access to procedures after Roe v. Wade was overturned.

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