Jeskewitz is the fourth Republican in the Assembly to announce they will not run again. Four Assembly Democrats also are retiring.
Republicans currently hold a 52-47 majority in the Assembly. Democrats have made gaining majority control of the chamber one of their top priorities in the fall elections and losing a Republican to retirement only helps.
Jeskewitz was first elected in 1996. She is co-chair of the joint Audit Committee.
The 66-year-old said Thursday she came to her decision to retire after months of soul-searching and deliberation.

