For any of those four, the group's endorsement before the nation's leadoff nominating contest could be a significant boost, given the outsized role religious and social conservatives have in the Hawkeye State.
Bob Vander Plaats, who founded the group, said in a statement that even narrowing the field to four proved difficult.
It ruled out Ron Paul because of concerns about his view on "states' rights as it pertains to the sanctity of human life and God's design for marriage." For Herman Cain, the board cited "a narrative of questions versus clarity on the key issues of life, marriage, foreign policy, and presidential readiness" in counting him out.
"The next step of final selection and recommendation to our supporters will be tougher," Vander Plaats said.
The Family Leader hosted a weekend forum that drew all of the major GOP candidates except Romney and Jon Huntsman. The group said it had no timeline for a final endorsement.