Go to:
http://www.mscode.com/free/statutes/23/015/0855.htm
This is the link Deport provided that appears to be the law on the subject (Oregon, TX, and PA are recent states that had special elections for resigning Senators). From glancing at it, it looks to me like there would have to be a special. But I will read it more carefully later. Deport, what does it look like to you? When would there be an election to replace Lott?
The link is to Mississippi law and has nothing to do with the other states you mentioned.....
Depends upon when the resignation occurred. If it's less than a year to a regular scheduled election then the regular election would be used. If over a year then there would be an election to fill the remained of the term.... the election would be within 90 days after the gov. issued the proclamation for the election... In either case the gov. would appt a replacement until the election decided the matter. that's my reading but someone can correct if I'm wrong.