insist that...must

[joham]

Some people insist that when a gerund is preceded by a noun or pronoun, the noun or pronoun must be in the possessive case.
They insisted we must wait until tomor

I read these sentences in THE AMERICAN HERITAGE GUIDE TO USAGE AND STYLE. I didn't know that 'insist that' could also be used with 'must' as well as the '(should) do/be' verb form. Are there any other verb forms that can go with 'insist that' (with the meaning of 'demand something happens or that someone agrees to do sth)?

Thank you in advance.

[JohnParis]

"...that can go with 'insist that'..."

Yes, many.
However, in my opinion, the force of the word "insist" is well matched with that of "must".

The following are also perfectly good sentences, but, to me, they seem less forceful when "must" is changed or removed:
1. Some people insist that when a gerund is preceded by a noun or pronoun, the noun or pronoun should be in the possessive case.
2. They insisted we wait until tomorrow.