Can’t find other sources that also say this date is definite, but 12/15 is apparently when Husted leaves (https://www.wsaz.com/2025/01/17/ohio-lt-gov-jon-husted-is-expected-succeed-jd-vance-us-senate-ap-sources-say/) so it certainly seems likely that the lame duck will include a switch of Senators. https://bsky.app/profile/emptywheel.bsky.social/post/3mzieds6jtc2t