A conservative group is launching an online ad campaign criticizing New Jersey Gov. Chris Christie's record on judicial nomimnations ahead of his trip to Iowa this week.

The Judicial Crisis Network is spending $75,000 on a digital media buy in Iowa to push a pair of online ads and a Web site blasting the Republican for not making the New Jersey Supreme Court more conservative.

"Chris Christie promised to change New Jersey's liberal Supreme Court," says the narrator of one of the ads. "Five openings later, no change. Instead, a liberal Democrat for chief justice."

Conservative activists were angered by Christie's renominaton earlier this year of the Democratic chief justice of the state Supreme Court, Stuart Rabner. It was part of a deal with Democrats that allowed him to install a Republican to fill a vacancy on the court.

"If what you want from public officials is to shy away from going for better rather than everything, then you know what you get? You get Washington D.C.," Christie said at the time in defense of his compromise.

Christie is slated to be in Iowa on Thursday, where he will attend three Republican fundraisers. The trip is sure to stoke fresh speculation about Christie's presidential ambitions, given Iowa's status as the first-in-the-nation presidential caucus state.