“In 1972 he was George McGovern’s nominee for Vice President, but withdrew after his psychiatric history was revealed (depression).”
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As I recall, the big issue was that Eagleton had undergone ECT (i.e. “electroshock therapy”).
Not so much.
In the bigger picture the problem was laid directly on George McGovern who first failed to vet his VP, then claimed to be "1000%" in support and finally dumped the hapless fellow.
McGovern was severely punished at the polls by voters.
McGovern's failure to properly vet Eagleton and his subsequent handling of the controversy gave occasion for the Republican campaign to raise serious questions about his judgment.
In the general election, the Democratic ticket won only Massachusetts and the District of Columbia."