In 1971, the then-president had appointed Bush as the U.S. ambassador to the United Nations.
In 1974, Bush was serving as the chairman to the Republican Party when details of the Watergate scandal surfaced about the then-president Richard Nixon. A break-in at the Democracti National Committee headquarters was connected to Nixon's reelection campaign. Burglars wire-tapped phones and stole documents, and Nixon scandalously attempted to cover his involvement in the crime.
Bush formally requested Nixon to resign from the presidency, which he did two days later.
Source: History and History