Kind has represented the seat since 1997.
An official announcement is expected soon, sources said. His office did not respond to a request for comment.
This a big blow for House Democrats, as his seat was a top target for the GOP in 2022 and will likely be even tougher to hang on to now. Kind is one of just seven House Democrats who represent a district carried by Trump in 2020 — and the second member from one of those seats to retire. Democratic Rep. Cheri Bustos of Illinois was the first.
Last November, Kind defeated GOP candidate Derrick Van Orden by fewer than 3 percentage points. Van Orden plans to run again.