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The quote I was looking for is in letter 246 and its terribly long so I will abridge it as best I can for the sake of this post. In the letter Tolkien gives his thoughts on Frodo, Aragorn, and Gandalf taking possession of the ring. The letter even makes reference to the difference in Frodo claiming the ring in his first encounter with the Nazgul vs. a possible encounter in the Cracks of Doom.

They were naturally fully instructed, and in no way deceived as to the real lordship of the Ring. The wearer would not be invisible to them, but the reverse; and the more vulnerable to their weapons. But the situation was now different to that under Weathertop, where Frodo acted merely in fear and wished only to use (in vain) the Ring's subsidiary power of conferring invisibility. He had grown since then. Would they have been immune from its power if he claimed it as an instrument of command and domination?
Not wholly. I do not think they could have attacked him with violence, nor laid hold upon him or taken him captive; they would have obeyed or feigned to obey any minor commands of his that did not interfere with their errand – laid upon them by Sauron, who still through their nine rings (which he held) had primary control of their wills. That errand was to remove Frodo from the Crack. Once he lost the power or opportunity to destroy the Ring, the end could not be in doubt – saving help from outside, which was hardly even remotely possible.
Frodo had become a considerable person, but of a special kind: in spiritual enlargement rather than in increase of physical or mental power; his will was much stronger than it had been, but so far it had been exercised in resisting not using the Ring and with the object of destroying it. He needed time, much time, before he could control the Ring or (which in such a case is the same) before it could control him; before his will and arrogance could grow to a stature in which he could dominate other major hostile wills. Even so for a long time his acts and commands would still have to seem 'good' to him, to be for the benefit of others beside himself.
The situation as between Frodo with the Ring and the Eight might be compared to that of a small brave man armed with a devastating weapon, faced by eight savage warriors of great strength and agility armed with poisoned blades. The man's weakness was that he did not know how to use his weapon yet; and he was by temperament and training averse to violence. Their weakness that the man's weapon was a thing that filled them with fear as an object of terror in their religious cult, by which they had been conditioned to treat one who wielded it with servility. I think they would have shown 'servility'. They would have greeted Frodo as 'Lord'. With fair speeches they would have induced him to leave the Sammath Naur – for instance 'to look upon his new kingdom, and behold afar with his new sight the abode of power that he must now claim and turn to his own purposes'. Once outside the chamber while he was gazing some of them would have destroyed the entrance. Frodo would by then probably have been already too enmeshed in great plans of reformed rule – like but far greater and wider than the vision that tempted Sam (III 177)5 – to heed this. But if he still preserved some sanity and partly understood the significance of it, so that he refused now to go with them to Barad-dûr, they would simply have waited. Until Sauron himself came. In any case a confrontation of Frodo and Sauron would soon have taken place, if the Ring was intact. Its result was inevitable. Frodo would have been utterly overthrown: crushed to dust, or preserved in torment as a gibbering slave. -letter 246

The letter goes on to mention a similar account of Aragorn's possession of the ring which ends in an encounter with Sauron which Aragorn cannot survive. He also implies that Galadriel or Elrond could have stood against Sauron with the One Ring in their possession, but that only Gandalf could have wielded it against Sauron unaided, since the majority of Sauron's might would be added to that of Gandalf's own considerable power.