Casey's letter Monday to Democratic National Committee Chairman Tom Perez says holding a primary debate in Pennsylvania would benefit the party in a state that holds great electoral importance to Democrats.
Casey said Democrats can't afford to lose Pennsylvania if they hope to beat President Donald Trump, after Trump in 2016 became the first Republican to win Pennsylvania since 1988.
Casey described Trump's victory as a "wake-up call" and said a debate in the politically divided state would help Democrats.
The DNC is planning a dozen debates, and has announced two locations - starting with Miami this June and Detroit in July.
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