nope
he was still a senator
although one could say that in effect he and McCain did little in the way of work as senators from Jan to the election last year
Bob Dole did resign though when he ran against Clinton. Really that should be required. They spend all their time on the campaign trail and do little work in DC.
On the other hand maybe we should make all of congress run for president and have to resign. We would be far better off with there being nobody running the country.
thank you froggy for clearing that up for me