DBWI: 1968 Election without the Kissinger Scandal

The Kissinger Scandal that broke in late October of that year obviously sunk the Nixon campaign. After all its hard to win an election when a key figure in a campaign is being publicly accused of treason for sabotaging peace talks.

Assuming it doesn’t break until after the election, how would President-elect Humphrey handle it? Or if Nixon somehow won in ‘68, how long would it take Congress to impeach him?
 
Without Nixon's politically motivated prosecution for treason after HHH's inaugeration, it probably takes longer for politics to devolve into shows of force and nothing more, much like the late roman republci. We know that in OTL, they stopped discussing issues in elections in what, the 80s or 90s.
 
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