[Mithadan]

Although Sam had borne the Ring for a short period of time, I doubt that the Ring or any other evil will played any part in Sam's debate. Rather, it was simply an internal dialogue brought on by extended weariness, deprivation and suffering. It could be summarized as "I can't go any farther... I must go on."

To the contrary, to the extent any external force was at work, it was likely a product of those who live in the West. Once Sam resolved to carry Frodo, he found that Frodo was light and was no great burden to him. While the West no longer was directly acting in Middle Earth as a physical presence, other than through the Istari, we cannot discount the ability and desire of the Valar to influence events. There are several mentions of Frodo having "fair" dreams while struggling along towards his goal. So maybe Lorien or others of the Valar had some hand in inspiring Sam to go on?