Democrat James Andrew Malone narrowly won a special election for a Pennsylvania state Senate seat in a stretch of Republican-leaning suburbs and farming communities, scoring an upset in a territory that a Democrat hasn’t represented in the chamber for 136 years.

Democrats won a significant upset victory in a Republican-leaning state Senate race in Pennsylvania, adding to recent GOP special election woes. Democrat James Malone narrowly defeated Republican Josh Parsons by less than 1 percentage point in the race for state Senate District 36 on Tuesday,

James Andrew Malone, a small-town mayor, won a special election on Tuesday, narrowly defeating a county commissioner in a district the G.O.P. held for decades.