Actually, I think if he resigns after the halfway point of his term there won’t be a special election.
He’s despicable enough that any term is undesirable.
He’s living openly in adultery. Even Bill Clinton did not do this.
But back to the original premise, if the plan is to elect Cochran and then have him resign (remember that he's suffering from dementia), then they can't wait for too long. A plan that waits for 3 years is not practical. Cochran can't be hidden from the people for that long.
On the other hand, there is also the Tim Johnson precedent, where he was absent for a year due to his brain hemorrhage. He refused to step down, which meant that the governor couldn't appoint a replacement. South Dakota went without a Senate vote for a year.
I don't think that is Barbour's idea of a plan. He wants Cochran out sooner rather than later so he can get his choice in place now.
-PJ