The 1990 Pennsylvania Gubernatorial Election, a contest between Popular Pro-Life Democratic Governor Robert P. "Bob" Casey Sr. and Newly minted State Auditor Barbara Hafer resulted in the Largest win for a Democratic Gubernatorial candidate in PA History
Finally winning the governorship after three unsuccessful tries, beating Philadelphia DA Ed Rendell (D) and Lt. Gov William Scranton (R) Casey's first term was considered a success.
Accomplishing things such as not increase taxes in his term, spearheading infrastructure projects, environmental regulations, local business protections, increasing funding for Education, Elderly care, & pre-natal care in addition to passing abortion restrictions in 1989
Sufice to say, it would've been difficult for any Republican to take down Casey, but Hafer - a deeply unskilled candidate despite having been elected statewide - made several blunders that ended up blowing up casey's margin.
Among them were calling Casey an "Irish Redneck from Scranton", critizising Barbara Bush, one of the most popular republicans in the country, and a debate in which as the Philadelphia Inquirerer put, she "disqualified herself with an 'uh'-sprinkled performance".
Contrast this with Casey's image created in his 1986 campaign as a traditional wholesome Pennsylvania family man as well as his successful term and it's no wonder why the popular governor won in a historic landslide
Bob Casey won 66/67 Counties to Haefer's 1/67, All 23 Congressional Districts to HAefer's 0/23, 49/50 SDs to Haefer's 1/50, and 190/203 HDs to Haefer's 13/203