From 1979 to 2019, he was a long-standing member of the Pennsylvania State Senate.
He served as the representative of the 12th District, which includes parts of eastern Montgomery County and southern Bucks County.
From 1970 to 1977, Stewart John Greenleaf Sr was an assistant district attorney in Montgomery County.
He also served as an assistant public defender in Bucks County.
He was elected as a Commissioner for his birth-town of Upper Moreland Township, Pennsylvania In 1971.
Following his first term, he was elected to a seat in the Pennsylvania House of Representatives in 1976.
Greenleaf served a single term in the house before winning his bid for the State Senate in 1978.
Greenleaf was reelected to Congress seven times.
Greenleaf dropped out before the county endorsement convention after he considered to run for U.S. Congress in 1993, briefly forming an exploratory committee to challenge Marjorie Margolies.
He ran for Congress against officeholder Joe Hoeffel, in 2000. Greenleaf had addressed a large part of the eastern bit of the legislative region for just about 25 years.
In the end, Hoeffel won the race with nearly 53% of the vote to Greenleaf’s 46%.
He didn’t need to surrender his state senate seat to run for Congress; Pennsylvania state representatives serve staggered four-year terms, and Stewart Greenleaf was not on the ballot until 2002.
In his last term, he was Chairman of the Senate Judiciary Committee and served on the Appropriations, Banking and Insurance, Consumer Protection and Professional Licensure and Environmental Resources and Energy Committees. In 2018, he decided not to run for re-appointment.
He embraced his child, previous Montgomery County regulator, Stewart Greenleaf Jr., as his replacement.
Nonetheless, Stewart Jr. was crushed by Democratic challenger Maria Collett.
Stewart John Greenleaf Sr continued to work as an accomplice in his law office, Elliott Greenleaf, whose lawyers incorporate Montgomery County Commissioner Bruce Castor and previous State Rep. Melissa Murphy Weber.
Stewart John Greenleaf Sr graduated with a class of 61 at The University of Pennsylvania and the University of Toledo College of Law.
Greenleaf passed away at 81 years old on February 10, 2021.