On this day he ended the doubt, he refused to sign it.
Carranza was a tough minded individual. He never liked Woodrow Wilson and he had a grudge against the United States. Irrespective of what may seem to be the advantages of the proposals that were made, he wouldn't agree.
And he never did. Carranza never executed a protocol with the United States.
By this point the United States clearly wanted out of Mexico. The intervention had bogged down to an uneasy occupation since the summer and was going nowhere. Carranza guessed correctly that the United States would be leaving no matter what, although that did not mean that the US would be passive in protecting its interests.