2018 Pennsylvania Senate election
The 2018 elections for the Pennsylvania State Senate were held on November 6, 2018, with 25 of 50 districts being contested. Primary elections were held on May 15, 2018. The term of office for those elected in 2018 began when the Senate convened in January 2019. Pennsylvania state senators are elected for four-year terms, with half of the seats up for election every two years.
Republicans had controlled the chamber since the 1994 election.
Overview
Republicans had controlled the chamber for years. Democrats won five seats but failed to retake the majority despite winning the popular vote by over 200,000 votes. However, in five contests a Democrat ran unopposed with no Republicans appearing on the ballot. Republican senator Randy Vulakovich of the 38th district was the only incumbent to be defeated in the primary elections, losing to Jeremy Shaffer, who in turn lost to Democratic candidate Lindsey Williams in the general election. Two other Republican incumbents – Thomas J. McGarrigle and John Rafferty Jr. – were also defeated in the general election by their Democratic challengers. In the 10th district, Republican Chuck McIlhinney chose to retire, and his seat was won by Democrat Steve Santarsiero, while in the 12th district, Republican Stewart Greenleaf retired and was replaced by Democrat Maria Collett.Close races
Ten district races had winning margins of less than 15%:| District | Winner | Margin |
| District 6 | Republican | 0.06% |
| District 10 | Democratic | 5.06% |
| District 12 | Democratic | 5.38% |
| District 16 | Republican | 2.84% |
| District 24 | Republican | 5.82% |
| District 26 | Democratic | 8.58% |
| District 34 | Republican | 11.52% |
| District 38 | Democratic | 0.64% |
| District 40 | Republican | 12.59% |
| District 44 | Democratic | 3.94% |