Billionaire John Childs, 77, donated $2,700 to Grassley Committee, Inc. in 2016.

IOWA -- Senator Chuck Grassley told Iowa reporters on Wednesday that he has two restrictions for campaign donations, and that a donation from a man who was caught in a trafficking case in Florida met both of them.

Billionaire John Childs, 77, was charged in the same sex trafficking sting that resulted in Robert Kraft's arrest. Childs donated $2,700 to Grassley Committee, Inc. in 2016.

"I have two restrictions on campaign contributions. In other words, as long as these restrictions are met, I take any contribution people want to give me," Grassley said. "No strings attached and it's legal... In this instance, neither one of those were an issue."

Grassley said he didn't know the name John Childs.

This comes after a progressive advocacy group, Progress Iowa, called for the Grassley and Jeff Kaufmann to give back the donations.