WASHINGTON — When the Sandy Hook school shooting rocked the country, Pennsylvania Sen. Bob Casey changed his longtime stance on the Second Amendment, becoming a fierce advocate for stricter gun laws. When a Supreme Court decision neared that would make same-sex marriage legal nationwide, Casey embraced the shift, abandoning his previous objections. And when President Joe Biden took office early last year, Casey softened his stand on the Senate filibuster, suggesting he’d be open to changing the rule if it helped Democrats turn big, progressive ambitions into reality. But as Casey has followed …
