: : : : Bilbo also had a stronger will than Sam and Frodo and seemed to be able to withstand its influence for a longer period of time.

: Then again, the ability to resist the influence could have been tied to Sauron's strength. At the time of The Hobbit, Sauron was regaining his strength, and had not reach his full power.

:
: : Bilbo never had his will tested to the degree that Frodo did, he was never tempted to use the Ring in such critical situations. We have no basis to judge how he'd have handled the stresses and temptations that Frodo (and Sam) faced.

: A critical situation depends on a person's point of view. I'm sure there were situations that Bilbo believed were indeed critical. That aside, I have long held the theory that knowledge of the ring's true nature played a great part in temptation and tests of will. Bilbo did not know the true nature of the ring at the time of The Hobbit, neither did Gandalf. At the time of Elrond's council in Rivendell, Gandalf knows the true nature. He refuses to bear the ring because he would be tempted. This brings up an interesting question. Would Boromir have tried to take the ring from Frodo, if he had not known the ring's true nature?

actually, Bilbo never stood the temptation. he used the ring constantly, even to avoid some merely unpleasent situations.