Rep. Steve King (R-Iowa) is hitting back against American Crossroads President Steven Law in a new fundraising e-mail, declaring: "Nobody can bully me out of running for Senate."

King, a deeply conservative congressman with a tendency to make controversial utterances, has come under scrutiny from Republican strategists who worry he will make a bid for retiring Democratic Sen. Tom Harkin's seat.

"We’re concerned about Steve King’s Todd Akin problem,” Law told the New York Times in a story published over the weekend. Law is leading a new effort to recruit electable GOP Senate candidates and protect them from the ones viewed as less electable.