At the time of the Tonkin Gulf Resolution [wikipedia.org], 90% of American's supported deeper involvement.
At the time, the American people were being lied into supporting a war, so it's hard to take that number seriously as an indication of truth.
The Maddox fired on ghost ships (RADAR errors) and the Johnson administration explained it as "another attack", insisted the NVA fired first, and sold this as evidence of a pattern of aggressive behavior that had to be dealt with.
50,000 Americans died fighting a boogey man, and killed many more innocents than that. But the MIC profited handsomely, just as Eisenhower had predicted.
The NSA's report was only declassified after the Bush Administration lied Americans into war in 2003, but now we have two documented examples of being lied into war by the USG. It's no wonder that they didn't bother seeking any authorizations for any of the subsequent wars in the Middle East or Africa.