Well, among the amendments I suspect had less than 35% strong support are: 26th, 25th, 24th, 23rd, 22nd, 20th, 18th, 15th, 14th, 12th, and 11th. I don't consider the 27th because of the strange way in which it was ratified.
IF an amendment secures 66% of the Congress and 75% of the legislatures for no reason other than fear of voter backlash, I assert that is tantamount to "mob rule." Can you think of any other amendment that even remotely qualifies????
I don't see anything there about a support threshold. In fact, the statement could in theory apply to an issue with even 95% strong support.....