I have heard the resident has to serve sometime into his second year, it may be the entire year, but I'm not certain. I heard this when Kamala was thought about taking over--she wouldn't take over before that date because then she couldn't run for the next term. If she waited, then she could run for a second term because she didn't serve the bulk of the first term (I may not have explained that right, but I think I put the gist of it in there, hopefully).