Bruce Rastetter is the kind of Iowa Republican activist how can get a private meeting with a presidential candidate. He's a very successful agri-businessman who donates generously to GOP causes. The Des Moines Register included Rastetter in there list of the 50 most wanted Iowa Republican operatives.

The Center for Responsive Politics notes in the last three federal cycles, Rastetter has written checks totaling more than $180,000 to candidates, committees and party organizations. He is what some operatives refer to as a "whale"...a very deep-pocketed donor.

But this time around, Rastetter has parked both his money and his support. He also was among a group of Iowan who visited NJ Governor Christie to urge him to run for president.

This week Rastetter sat down for an interview to talk about why he and other big Iowa donors are holding back... and what they might be looking for before they throw their support and money behind a candidate.

Steve Brown is an author, radio broadcaster and seminary professor at Reformed Theological Seminary in Orlando, Florida.