Diehl (born April 23, 1969) is a Republican politician who represented the 7th Plymouth District (Abington, Whitman, and East Bridgewater) in the Massachusetts House of Representatives.
He was a member of the Joint Committee on Housing, House Committee on Global Warming and Climate Change, and the House Committee on Technology and Intergovernmental Affairs.
Diehl also served as a member of the House Library Caucus and Regional School Caucus.
On November 2, 2010, he upset incumbent Allen McCarthy and was sworn in on January 5, 2011.
He served as Donald Trump's Massachusetts campaign co-chair during the 2016 presidential election.On November 6, 2018, Diehl lost the U.S.
Senate election in Massachusetts to Democratic incumbent Elizabeth Warren.