Brown's administration was weird. It was economically pretty right of center aside from environmental and labor policy. Socially very liberal, to the point that he irked a lot of members of his own party. And he had those pet projects that gave people a national patriotic excitement.
Considering how into boosting NASA he was, no wonder he picked John Glenn as running mate.
National VAT, simplifying the tax code to two rates, minimum income (funded by modest payroll increase, estate taxes, land-value tax, leasing fees on federal lands, and natural resource extraction taxes), nixing lots of deductions, reverse engineering bussing (open enrollment plus "distance vouchers" for public schools pretty much creating the same effect), boosting the state infrastructure bank, creating the
AERPA energy-research program, boosting NASA, deregulation (energy, airlines, trucking, shipping, killing the jones act, finance, alcohol), decriminalizing marijuana, appointing gay judges, decriminalizing "homosexual conduct", financing primary care clinics, tax deductions for healthy living, reforming the FDA to simplify the drug approval process in the face of the AIDS Crisis, passing the balanced budget amendment, passing the national popular vote amendment after Carter got screwed in 76, passing the line-item veto amendment, passing the
Wyoming Amendment, balancing the budget and generating a surplus, allowing nurse practitioners to open their own practices (as well as funding other weird stuff, like acupuncture and midwifery), getting persons living in common the right to visit one another in the hospital (great for gay rights), appointing gay judges, working hard to get Harvey Milk elected to Congress, expanding the national parks, getting more environmental protections passed, boosting Americorps (so that voluntary national service would guarantee people a modest annual pension and free education at any state or community college), getting the nonvoting House Members the right to vote in Congress (Jesse Jackson from DC, the Cherokee and Choctaw Representatives, Representatives from PR, USVI, Guam, and American Samoa), getting us a big ol' budget surplus, surveillance reform, whistleblower protections, lobbying reform, making Cesar Chavez the Secretary of Labor, etc.
Simply put, the Dems were in a tailspin in 1996 - the plane crash that took out President Gore left the Dems in a world of hurt, especially since Dukakis was a complete fuckup in office. Dukakis didn’t want the job, the Dems didn’t want him, and everyone knew John McCain was getting the win in 1996.
The 90s were weird, though - coming off four years of Dollars and Sense Donald, the Gore tragedy, Dukakis being ineffective, and then leading us into McCain thwarting an attack on the World Trade Center and all but discrediting the religious right.
Then-Secretary Rumsfeld was probably the only Republican who could have won in 1988. The Brown Administration was broadly pretty popular, even with a lot of folks who didn't like his social policies, and Vice President Glenn basically promised all the good of Brown with a bit less weirdness and a bit more midwestern wholesomeness.
Rumsfeld was seen as the face of the Ford Administration's supporting Iran and Afghanistan in their struggle against the Soviets, so there was a lot of goodwill on the part of the public towards him. Movement conservatives also loved him because of his being a pretty hardcore free marketeer and fairly hawkish. He also supported the Civil Rights Act and did decently in picking Jack Kemp as his running mate (managing to both double down on economic conservatism but also broaden the ticket's appeal as well). Rummy's Pro-Israel positions also helped a bit with Jewish and fundamentalist Christian voters.
Rummy had significant Foreign Policy Achievements to his name, economic accomplishments, educational accomplishments, etc. What screwed him in 92 was that the ACes forced the election to the House of Representatives and the Democrats controlled the House and Senate.
McCain invading Sudan over their harboring of Bin Ladin was a bit of mess. The US unilaterally chopping a country in three also was a precedent that caused issues down the line.