President Bush’s approval rating fell at the end of his presidency in part because he

He promised to not make any new taxes. However, this turned out to be false and he did raise the taxes.

[ this is the basic answer. there is a better explanation below. hope this helped!!!]

Explanation:

GHW Bush ran on a platform that literally promised no new taxes. He famously said in his 1988 acceptance speech

Read my lips: "No new taxes!"

The problem was in 1990 Bush wanted to break a budget deadlock. The only way to do that was to compromise with Democrats and raise taxes

In September 1990, two years into George H.W. Bush’s first term, the United States was saddled with a $200 billion budget deficit. Months of partisan wrangling over possible tax increases and spending cuts had ended in a stalemate.

Despite the potential political backlash, Bush announced a compromise with congressional Democrats that would cut $500 billion from the deficit in five years, in part by raising “luxury taxes” on items including yachts and pricey cars, among other tax hikes.

It is still widely regarded as the reason why he lost the 1992 election

originally he was supposed to be dead but they wanted to continue the series so they brought him back to life.