Nixon’s more egregious mistake was to fail to challenge the stolen election of 1960, when the cemeteries of a few Chicago districts put JFK in office. For the good of the country...
He just put his aides and Republican leadership out to challenge it. Nixon in my opinion was savvy in how it was handled so as not to muddy himself personally in the process. Besides there was most likely fraud on both sides.
And Texas. Johnson’s ability to fix things there got him his spot on the Kennedy ticket.