HARRISBURG — U.S. Sen. Bob Casey is endorsing Katie McGinty in the four-way Democratic primary to determine who will face first-term Republican U.S. Sen. Pat Toomey.

Braddock Mayor John Fetterman, Joe Vodvarka, and Joe Sestak — a former congressman who Toomey defeated for the Senate seat in 2010 — are the others running for the Democratic nomination.

McGinty was secretary of the Pennsylvania Department of Environmental Protection under former Gov. Ed Rendell and briefly served as Gov. Tom Wolf’s chief of staff before resigning to run for the Senate.