A Republican congressman in one of this fall’s key U.S. Senate races helped secure earmarks for three former clients of the lobbying firm where his son is an executive, records show.

In an unusual twist, U.S. Rep. Denny Rehberg of Montana, who is in a hotly contested race with first-term Democratic Senator Jon Tester, co-sponsored earmarks with Tester for MSE Technology Applications, the Rocky Boys Indian reservation and Salish Kootenai College.