LINCOLN, Neb. (AP) — Nebraska Gov. Pete Ricketts is refusing to comment on the presidential race even after Republican front-runner Donald Trump blasted his family on Twitter.

Ricketts said Tuesday he is waiting for the GOP field to narrow before making remarks about the candidates.

Trump tweeted Monday that the Ricketts family should “be careful, they have a lot to hide” in response to reports that the super PAC founded by billionaire Joe Ricketts has financed attack ads against him. Joe Ricketts is the governor’s father.

Ricketts says he cannot guess what secrets Trump is referring to, and notes that Trump misspelled his family’s name.

Ricketts says he does not know if he will endorse a candidate, but would back someone who embraces Ronald Reagan’s policies.